In the February 24, 2015 cold snap, NOAA's station at Freeville, a village on the flat floor of an old glacial lake where Virgil Creek meets Fall Creek, read −29°F. In the same cold snap Cornell's station on East Hill read −22°F, and the Aurora research farm near the shore of Cayuga Lake, just north of this map, read −6°F. That 23°F spread is most of what you need to know about fruit trees for Ithaca, Cortland and Cayuga Lake: the open lake and the slopes above the valleys run warm, and the flat creek valleys out in the uplands fill with cold.
The map covers the south third of Cayuga Lake up to King Ferry and Interlaken Beach, Ithaca and its three hills, Lansing and Trumansburg, the uplands east through Dryden, Freeville and Groton to Cortland and Homer in the Tioughnioga valley, and south to Newfield, Danby and Brooktondale. Type your address in the box on the map to get the number for your own place, and the list of what we sell that has come through it.
How to read this map
The big number at any spot is its 30-year planning low, the bad winter night we'd plan a tree around, cautious on purpose and not a promise of how often that night comes. The MFTC zone is that number in half zones; the typical winter is an average year's coldest night, the kind of number USDA's map is built on. The spring layer shows how many degrees warmer or colder a spot runs than downtown Ithaca on a still, clear night at bloom.
The middle of the growing ground plans for −24°F, the coldest 5 percent −27°F or colder and the warmest 5 percent −21°F or warmer. Downtown Ithaca, the reference, plans for −25°F (MFTC 4a, typical winter −11°F), and Cortland −25°F, right on the line between 4a and 4b. Harford, Harford Mills and Freeville, at −29°F, are the coldest named places we checked. Yellow Barn Hill (−18°F) and Mount Pleasant (−19°F), both MFTC 5a, are the warmest named places we checked. Downtown's −25°F is colder than anything NOAA's Cornell station has recorded since 1995 (−22°F, in 2005 and again in 2015) and matches that station's all-time low from 1957 and 1961.
Why the map looks the way it does
Two drainages meet here. Cayuga Lake runs north to Lake Ontario, while Cortland and Homer sit in the Tioughnioga valley, which runs south to the Susquehanna. The lake, at about 382 feet, fills an overdeepened glacial trough, and its creeks drop to it in gorges (Fall Creek, Cascadilla, Taughannock) from hanging side valleys up to about 390 feet above the floor. Around it the Finger Lakes Uplands rise to 1,000 to 2,000 feet, topping out at Virgil Mountain, about 2,110 feet, southeast of Cortland.
On a clear, calm night most of the cold is made right on the valley floors as the ground loses heat to the sky, and side valleys pour more onto them. Many floors east of Ithaca are old lake beds: as the ice retreated, proglacial Freeville-Dryden Lake stood at about 1,060 feet in the Fall Creek valley, and Freeville sits on its floor. That lake spilled through the steep-walled head of Ellis Hollow, the narrow old spillway in the Cascadilla Creek valley, and Cornell researchers working in Ellis Hollow saw big temperature differences over short distances, the kind a coarse climate grid misses. Wide, flat basins like Freeville's pool hard. NOAA's Freeville station runs a median 4°F colder than Cornell's on the year's coldest night, and the Ithaca 13 E station, 13 miles east of the city at 1,228 feet, 3°F colder. Around Dryden, Harford, Brooktondale and Caroline the benches 100 to 700 feet up plan 4°F to 5°F warmer than the floor, against about 3°F around Ithaca and Cortland.
Above the floors sits the warm belt. NOAA's Mount Pleasant Farm station, 1,650 feet up on the hill east of Ithaca, ran a median 6°F warmer on the year's coldest night than Cornell's station 4 miles away and about 700 feet lower, and in the February 2, 1961 cold snap it read −17°F to Cornell's −25°F and Cortland's −26°F. We haven't found a published explanation, but it fits a hilltop sitting above the valley's cold pool, and the map plans Mount Pleasant at −19°F.
The belt has limits. When arctic air pours in on a wind there's no inversion and higher ground runs colder. In the December 25, 1980 cold snap the Tully Heiberg Forest station, at 1,899 feet on the map's edge, read −29°F while Cornell read −12°F, which fits that kind of night. Ithaca knows the stormy-day version too, when it rains downtown and snows at Cornell. Plant the upper slopes and benches, not a bald, windswept top.
Cayuga Lake is the other warm sink. It averages 179 feet deep and passes 430 feet at its deepest, and the deep water stays 37°F to 41°F all year. Open water keeps its shore warmer in winter: NOAA's Aurora farm station has an average yearly low of −8°F against Cornell's −11°F and Freeville's −15°F. A Cornell vineyard-siting paper reports the effect at Lodi on Seneca Lake, just west of here, where a hilltop 550 feet above the lake ran 5°F colder than the ground near the water on 15°F nights and about 15°F colder in the extreme ones. Near open water, the low ground is the warm ground.
The map shows that reach along the shore. King Ferry Station plans for −21°F and Kidders and Lansing Station −22°F, but toward Ithaca it fades to −25°F at McKinneys and −26°F in the Northside Triangle by the Inlet. That fits the lake's shape: its south end is shallow and often freezes, and frozen water does nothing for its shore.
Soil follows the old lakes too. Glacial Lake Ithaca's shoreline sat near the 1,000-foot contour, and around Fall Creek and Cascadilla Creek the ground below it is mostly gray, limy lake clay and silt, with beach gravel ridges just under 1,000 feet and small deltas, one of them in the southern Cornell Orchard. Cornell's home fruit guide asks for well-drained soil, so on the clay test drainage before you plant (dig 2 feet, fill, let it drain, refill: under 10 hours is well drained).
Ithaca's flats: Downtown, Fall Creek, Northside, the West End and Southside
Ithaca grew on the flats at the head of the lake, about 404 feet up, on silt that filled the old south end of Cayuga Lake. Fall Creek and Cascadilla Creek come out of their gorges onto the flats, Six Mile Creek and the Inlet come in too, and on a still night they bring cold off the hills. Downtown and the Commons plan for −25°F (MFTC 4a, typical winter −11°F). The rest of the flats plan for −26°F: Fall Creek, toward Stewart Park, reads 2°F colder than downtown at bloom (spring flooding is a concern there, so use the high side of the lot); the Northside Triangle and the West End along the Inlet read about even; Southside 1°F colder; Titus Flats and the Cherry Street industrial park 2°F colder. The benches within 3 miles plan for −23°F.
Is downtown warmer? The sources split. Cornell Cooperative Extension of Tompkins County says downtown runs about a whole growing zone warmer than the rest of the county, with about two extra frost-free weeks at each end. Wikipedia says the valley flats run slightly cooler in winter. There's no NOAA station on the flats in our records, and we haven't found a heat-island study for Ithaca. The map has a foot in each camp: downtown is 3°F to 4°F warmer than the upland floors at Dryden (−28°F) and Freeville (−29°F), but 1°F to 2°F colder than the hillsides right above it. Buildings and pavement hold heat on still nights, while the flats catch the cold draining off three hills.
Give the flats apples, plums and tart cherries rated −30°F and colder. A south or west wall helps a tender tree through winter but pushes its bloom earlier, so save the apricots and peaches for the hills.
East Hill, Collegetown, Cayuga Heights, South Hill and West Hill
East Hill rises between the Fall Creek gorge and Six Mile Creek with Cornell on top, where NOAA's Cornell station (960 feet, records back to 1893) has its own 30-year number of −24°F. Collegetown, a hillside about 320 feet above the flats where cold drains past instead of settling, plans for −24°F (MFTC 4b, typical winter −9°F) and reads 12°F warmer than downtown at bloom, the best bloom-night reading of any Ithaca neighborhood we checked. East Ithaca plans for −24°F and reads 10°F warmer. Cayuga Heights runs from about 900 feet near Community Corners down to about 400 feet at the lake; the village plans for −23°F and reads 10°F warmer, while down by the water at Renwick it's −24°F and only 2°F warmer. Forest Home plans for −24°F and Northeast Ithaca −23°F. For Cornell Heights and Belle Sherman, type in your address.
South Hill, up NY 96B toward Ithaca College, plans for −23°F on a bench 610 feet above the floor and reads 10°F warmer. West Hill climbs from Floral Avenue up Trumansburg Road toward Cayuga Medical Center; its lower slope plans for −24°F and reads 11°F warmer, and Northwest Ithaca, 510 feet up, −23°F and 10°F warmer. West of the city the low spots turn cold again: Enfield and Bostwick Corners plan for −26°F and read 2°F and 6°F colder at bloom.
These slopes are Ithaca's ground for stone fruit. Blushingstar peach (−25°F) clears them with a degree or two to spare, and it came through −25°F at our place on January 13, 2024 without damage. Contender (−30°F) and Siberian C (−35°F) peaches have more room; Tom McCamant grows Contender at Forbidden Fruit Orchard in Paradise, Montana, and it's the only commercial peach we know of that has taken −32°F. Add Harlayne apricot (−30°F), Black Gold sweet cherry (−35°F), which Cornell's home fruit guide lists among the crack-resistant ones, and Seckel pear (−35°F), fire blight tolerant per Cornell.
Lansing and the east shore to King Ferry
Lansing runs up the east shore from Ithaca. Lansing village, at the town's south line, plans for −23°F (MFTC 4b, typical winter −9°F) on a bench 460 feet above the floor and reads 3°F warmer than downtown at bloom. South Lansing plans for −24°F and reads 8°F warmer; Myers, where Salmon Creek comes in, −24°F on a terrace 100 feet above the water and 10°F warmer; Lake Ridge −22°F and 9°F warmer. NOAA's station at the Ithaca airport, which sits partly in Lansing village, has a 30-year number of −22°F, and its coldest since 1995 was −20°F, in the same 2014-15 winter that took Freeville to −29°F.
Farther north, King Ferry plans for −22°F (typical winter −7°F), and Ledyard, Bowers Corner and Five Corners, on benches 220 to 340 feet up, −21°F. Genoa, on a toe slope, is the exception at −26°F. This is good ground for Bartlett (−35°F) and Harrow Sweet (−30°F, on Cornell's pear list) pears, Italian (−35°F) and Stanley (−30°F) plums (Stanley is very prone to black knot) and Westcot apricot (−45°F).
Trumansburg, Taughannock and the west shore
Trumansburg sits at about 965 feet on the west side, about 12 miles north of Ithaca, built around a cascade on Trumansburg Creek, which reaches the lake at Frontenac Point. The village plans for −23°F (MFTC 4b, typical winter −9°F) 250 feet above its floor but reads only 1°F warmer than downtown at bloom. Taughannock Falls hamlet, on the bench at 843 feet, plans for −22°F and reads 11°F warmer, Willow Creek −23°F and 11°F warmer, Covert −22°F and 7°F warmer. Down at the water, Kidders, Atwaters, Cold Springs and Interlaken Beach plan for −22°F, and Sheldrake Point, on a point that sticks out into the lake at Ovid, is known as a very protected site.
Back from the lake it's a different story. NOAA's old Perry City station, at 1,038 feet (1893 to 1913), ran a median 6°F colder than Cornell's on the year's coldest night. The map has Perry City at −25°F, and Waterburg, just northeast in a draw, at −24°F but 8°F colder at bloom. That's an old record, but it's a reason to give the low ground out there some room. On the benches and shore, grapes join the list: Marquette (−35°F), La Crescent (−40°F) and Concord (−30°F). Cornell's home guide wants at least 150 frost-free days for grapes, which the shore has.
Dryden, Freeville, Groton and Harford: the cold flats
East of Ithaca the uplands open into wide, flat creek valleys, the cold heart of the map. Freeville, at about 1,043 feet, plans for −29°F (MFTC 4a, typical winter −14°F) and reads 4°F colder than downtown at bloom, matching the 30-year number of NOAA's station there. Red Mills, in a draw northeast of the village, plans for −28°F and reads 8°F colder. Dryden village, at about 1,089 feet with Virgil Creek running through it, plans for −28°F (typical winter −13°F); within 3 miles the floor plans for −28°F, the benches −24°F and the warmest tenth of the growing ground −21°F. West Dryden, on a bench 210 feet up, plans for −22°F and reads 6°F warmer; Varna plans for −25°F and Etna −27°F.
Groton, at about 997 feet on the shallow Owasco Inlet, plans for −28°F and reads 4°F colder at bloom, McLean −27°F and 5°F colder, and Locke, on a river bottom at 796 feet, −28°F. Harford, southeast of Dryden at about 1,204 feet, plans for −29°F (typical winter −14°F) and reads 5°F colder. Up on the hills, Hammond Hill plans for −20°F (MFTC 5a), and Star Stanton Hill and Turkey Hill −21°F, both 14°F warmer at bloom, the warmest spring readings of any named places we checked.
On these floors plant trees rated −35°F and colder and leave room: Haralson (−45°F) and Zestar!® (−40°F) apples, Kerr (−50°F) and Centennial (−50°F) applecrabs (Ed Schultz saw zero winter injury on Centennial after a winter that hit −47°F), Black Ice plum (−40°F) on any rise and Meteor tart cherry (−40°F). Trees rated −30°F clear Freeville by 1°F, which is no room at all.
Brooktondale, Caroline, Danby and Newfield
Southeast of the city the ice pushed up the Six Mile Creek valley as far as Slaterville Springs, and the bottoms run cold. Brooktondale, at about 915 feet, plans for −26°F (MFTC 4a, typical winter −12°F) and reads 4°F colder than downtown at bloom; within 3 miles the floor plans for −26°F, the benches −22°F and the warmest tenth −20°F. About 2 miles south of the village, at just over 980 feet, is the old outlet where glacial Lake Ithaca drained south into Willseyville Creek. Slaterville Springs plans for −26°F and reads 3°F colder, and Caroline −27°F. Climb a little and it turns: Besemer plans for −25°F and reads 4°F warmer, Caroline Center −22°F, Steventown Hill −20°F (MFTC 5a).
Danby plans for −25°F and reads 1°F colder. Newfield, at about 1,050 feet, plans for −23°F (MFTC 4b, typical winter −9°F) on a hillside 260 feet over its floor and reads 4°F warmer; the Newfield floor plans for −26°F. Littletree Orchards, on Shaffer Road, has grown apples here since the early 1970s. Richford, in the southeast corner, plans for −28°F.
Cortland, Homer and the Tioughnioga valley
Cortland, the Crown City, sits at about 1,129 feet on a plain where seven valleys come together; the seven points on the city seal stand for them. The Tioughnioga's West Branch starts at Tully Lake, a glacial kettle, runs through the Little York lakes and past Homer, and joins the East Branch at Cortland, and each of those valleys can send cold onto the plain on a still night. Cortland plans for −25°F, right on the line between MFTC 4a and 4b (typical winter −9°F), and reads 2°F colder than downtown Ithaca at bloom; the benches within 3 miles plan for −23°F. Cortland West, up a draw 150 feet over the floor, plans for −23°F.
NOAA's old Cortland station (1896 to 1998) holds the coldest reading of any station in our records here: −30°F, on December 30, 1917 and again February 9, 1934. Cortland also gets about 87 inches of snow a year, more than Ithaca, and snow insulates roots. Homer, about 2 miles north, plans for −26°F (MFTC 4a, typical winter −10°F) and reads 3°F colder at bloom. North on NY 281 the bottoms run colder at bloom: Pratt Corners 4°F colder, and Little York, at −27°F, 8°F colder, the coldest spring reading of any named place we checked. East Homer plans for −27°F and McGraw −26°F, 8°F and 7°F colder at bloom. Carr Hill and Hicks Hill east of the city plan for −21°F and read 12°F warmer.
The Cortland apple (−40°F) belongs here, along with Honeycrisp (−45°F) and Macoun (−35°F), Summercrisp pear (−40°F) on any rise, and Montana Black Currant (−50°F) and Red Lake currant (−40°F), which both fruited well for us in 2026 after their flower buds saw about 22°F.
Spring frost and bloom around Cayuga Lake
NOAA's 1991 to 2020 medians put the last 32°F frost at May 14 at Cornell's station and May 19 at Ithaca 13 E, and one year in ten May 27 and May 30. The last 28°F comes around May 2 at Cornell. At the Aurora farm by the lake the last 32°F comes April 29 and the first fall frost holds off to October 18, for 168 frost-free days against 146 at Cornell and 144 at 13 E. The Cayuga Lake AVA claims 165 to 170 days, where much of the Finger Lakes gets about 145.
The spring layer is the same drainage as winter, only stronger: the winter number moves about 6°F across the growing ground, but at bloom the named places run from 8°F colder than downtown (Little York, East Homer, Red Mills, Waterburg) to 14°F warmer (Turkey Hill, Star Stanton Hill). Most of the hillsides over Ithaca read 10°F to 12°F warmer and many benches above the lake 7°F to 11°F warmer, while most shore hamlets, at the foot of their slopes, read even with downtown to 4°F warmer.
The May 17 to 18, 2023 freeze came on a calm night that let the cold settle at ground level. Near Cayuga the stations barely dipped: Cornell's Lansing orchard 31.1°F with 2 hours below 32°F, the Aurora farm 30.6°F, Airy Acres at Interlaken 30.4°F, while Lakemont on Seneca Lake fell to 27.5°F with 8 hours below freezing. Cayuga's vineyards mostly came through, though neighbors ranged from almost no damage to total loss of primary shoots depending on elevation, the lay of the land and tree lines that held cold air. Up in Newfield, Littletree lost its whole apple crop, and some area farms reported losses up to 95 percent. We haven't found a Newfield temperature for that night, but it fits the lake holding up its shore while the uplands froze.
In 2012 an early heat spell followed by cold days took much of the region's apple crop. Hoffmire Farms in Trumansburg had none, while Indian Creek on West Hill had a full crop despite 22°F, which its grower credited to sugar-loaded blossoms. We can't place either farm's blocks, so we won't claim the map explains it, though it reads West Hill 11°F warmer than downtown at bloom and Trumansburg village 1°F warmer.
Site comes first; the FAO's frost manual calls it the single most important method of frost protection. Open blossoms of nearly every tree fruit start dying near 28°F (Michigan State's numbers), but only about 15 percent of apple blossoms need to set for a crop, and fully open haskap flowers take 19°F. Put apricots, peaches, plums and sweet cherries on slopes that read warm at bloom, and keep the bottoms for apples, applecrabs, haskap and currants. Don't dam a slope with a hedge or tree line across it, mow short through bloom, and water a day or two before a frost night.
What the weather records say
The coldest readings in NOAA station records here: −30°F at Cortland (1917 and 1934); −29°F at Freeville (February 24, 2015) and at two stations on the map's edges; −26°F at Perry City (1904); −25°F at Cornell (January 1957 and February 2, 1961); −24°F at Ithaca 13 E (January 21, 2005); and −20°F at the Aurora farm (January 14, 2004). Ithaca's zone is usually given as 5b to 6a and the Cayuga Lake AVA's as 6a and 6b, both built on the average winter. On the bad night we plan for, the flats and upland valleys are 4a, the hillsides and benches 4b and the highest hills 5a.
The lake freezes at both ends nearly every winter but end to end only rarely, and the lists of full freezes disagree; 1875, 1912 and 1934 are on every one. Timing matters as much as depth, too: Michigan tart cherry buds that died at about −12°F in November survived about −20°F in January, so we taper water from mid-August in zone 4 and colder.
What you can grow here
The lake shore, the benches above it and the high hills, −18°F to −23°F (King Ferry, Lake Ridge, Lansing, Trumansburg, Cayuga Heights, South Hill, Newfield). Trees rated −25°F and colder: Northern Spy (−30°F), Liberty (−30°F, scab resistant per Cornell) and Baldwin (−25°F) apples; D'Anjou (−30°F), Bartlett and Seckel pears; Stanley, Italian and Superior (−35°F) plums, with Toka (−45°F) to pollenize Superior (our pollination maps show what pairs with what); Black Gold and Lapins (−35°F) sweet cherries; Harlayne and Westcot apricots; Blushingstar, Contender and Siberian C peaches; Marquette and Concord grapes.
Ithaca's flats, the Cortland and Homer valley and the toe slopes, −24°F to −26°F (downtown Ithaca, Collegetown, West Hill, Cortland, Homer, Brooktondale). Trees rated −30°F and colder: Honeycrisp, Cortland, Empire (−35°F), Macoun and Liberty apples; Toka, Superior and Stanley plums; Montmorency (−30°F) and Evan's Bali (−45°F) tart cherries; Bartlett pear and Siberian C peach on a rise. Blushingstar is worth a try on the warmest of this ground.
Freeville, Dryden, Groton, Harford, Locke, Caroline and the cold bottoms, −27°F to −29°F. Trees rated −35°F and colder: Haralson, Honeycrisp, Cortland, Zestar!® and Wealthy (−50°F) apples; Kerr, Centennial and Trailman (−60°F) applecrabs (if you only plant one tree, make it Kerr or Trailman); Summercrisp pear on any rise; Black Ice and Toka plums on a rise; Evan's Bali and Meteor cherries; Honeyberry (−50°F) and Montana Black Currant.
Roots are the weak link, and snow cover protects them. Cornell's fruit specialists reported Geneva rootstocks coming through −40°F unhurt under about 6 inches of snow in 1994, while in 2004, after a thaw took the snow, nights near −25°F killed many Malling rootstocks. Of the two cherry stocks Cornell lists, Mahaleb has the hardier roots (they took 5°F in old tests that killed Mazzard roots at 12°F). The soils run limy (pH 6.5 to 7.5 in the AVA) and Cornell wants blueberries below pH 5, so our Cold Climate Blueberry Bundle (−40°F) needs an acidified bed. Cornell's trouble list runs to apple scab, fire blight, black knot, brown rot, plum curculio and bacterial canker on sweet cherry, and the hills take ice and heavy snow. Our cold hardiness calculator sorts everything we sell by the coldest temperature it has come through.
Fruit history here
The Cortland apple carries this county's name. S.A. Beach bred it at the state experiment station in Geneva in 1898 from McIntosh and Ben Davis; it was introduced in 1915, named after Cortland County, and is still one of the most widely grown apples in New York. Cornell has released 69 apple varieties since 1890, Empire, Macoun and Liberty among them, and Cornell Orchards went in along Route 366 in 1910. Steve Cummins, a sixth-generation grower, bought Indian Creek on West Hill in 1998 and grows about 60 apple varieties there. Visit Ithaca quotes a source calling the Seneca-Cayuga isthmus the most important cider region in the country. Ian and Jackie Merwin (he was a Cornell pomology professor) have grown heirloom apples at Black Diamond Farm since 1985. If you're down around Bath or Hornell, the Hornell, Bath and Canisteo map covers you.
Questions people ask
What growing zone is Ithaca, NY?
On the bad night we plan for, downtown Ithaca is −25°F, MFTC zone 4a, and the hillsides above it (Collegetown, Cayuga Heights, South Hill, West Hill) are 4b at −23°F to −24°F. Ithaca's zone is usually given as 5b to 6a; USDA's zones are built on the average winter's coldest night, and our typical winter for downtown, −11°F, fits 5b.
When is the last frost in Ithaca?
At NOAA's Cornell station the 1991 to 2020 median last 32°F frost is May 14, and one year in ten it comes after May 27. The last 28°F, where open blossoms start dying, comes around May 2.
Is downtown Ithaca warmer than the rest of the county?
Sources disagree: Cornell Cooperative Extension of Tompkins County says downtown is about a growing zone warmer, Wikipedia that the valley flats run slightly cooler in winter. Our map puts downtown at −25°F, 3°F to 4°F warmer than the upland flats at Dryden and Freeville but 1°F to 2°F colder than the hillsides right above it.
What zone is Cortland, NY?
Cortland plans for −25°F, right on the line between MFTC 4a and 4b, with a typical winter of −9°F. Homer plans for −26°F (4a). NOAA's old Cortland station holds −30°F, from 1917 and again 1934, so leave trees some room.
Does Cayuga Lake freeze over?
The shallow ends freeze most winters, the whole lake only rarely: 1875, 1912 and 1934 are on every list, and others add years like 1962, 1979 and 2015. A frozen south end stops warming the Ithaca shore, which fits McKinneys planning for −25°F and King Ferry Station, farther north, −21°F.
Can you grow peaches in Ithaca?
Yes, with a hardy tree on the right ground. Siberian C (−35°F) and Contender (−30°F) clear downtown's −25°F, and Blushingstar (−25°F) fits the hillsides at −23°F to −24°F. Plant them where bloom nights read 10°F to 12°F warmer than downtown, like Collegetown, West Hill, South Hill or the benches at Taughannock and Myers, not in the creek bottoms around Freeville and Brooktondale.
Warmer spots, colder spots
Here's the number to plan for at named places on the map, warmest first. Each one is the 1-in-30-year low for that spot: the cold hardiness calculator's number from the same weather stations, sharpened by our microclimate model for the ground right there. Zone is our MFTC zone, set by that one bad night, not by an average.
Runs warmer
Runs colder
How this map works
Every number on this map is a 30-year planning low, the same number our cold hardiness calculator gives. It's built from NOAA station records, leans a little cold on purpose, and gets nudged a degree or two for the ground right around you. The spring frost layer runs our full terrain model, which follows cold air down the draws and into the bottoms. It's a planning number, not a promise: how long the cold lasts, wind, soil and late-winter warm spells matter too.
The physics of cold air, how the number is built, every terrain weight and the limits of the model are all on one page: how our microclimate maps work.
The weather stations behind it
These are the long-record stations in and around this map, with each one's own numbers since the winter of 1995-96. The last column is this map's 30-year number right at the station, which won't match the station exactly: it's a blend of the stations around it, the way the calculator works everywhere.
| Station | Elev (ft) | Winters | Coldest since 1995 | Average winter low | 1-in-30 low | Map here |
|---|
Source: NOAA records through ACIS, winters 1995-96 through 2025-26. What the "carried forward," "gaps filled" and AWOS rows mean is explained in how our microclimate maps work.
Take your spot to the calculator. Click your ground on the map, then open the cold hardiness calculator at that spot. It will show you every plant we grow that has come through that cold.
Open the cold hardiness calculator