USDA Hardiness Zone 6b
Frost Dates for 06250 — Mansfield Center, Connecticut
NOAA 1991–2020 normals from Willimantic Windham Airport, CT (247 ft), 2 miles southeast.
Updated
In Mansfield Center, the last spring frost (32°F) is around April 28 in half of years and has passed by May 11 in nine years out of ten. The first fall frost comes around October 13, as early as October 2 one year in ten, leaving a typical freeze-free season of 167 days (NOAA, Willimantic Windham Airport, CT).
- Last spring frost
- April 28
- First fall frost
- October 13
- Growing season
- 167 days
- Hardiness zone
- 6b
50% probability
50% probability
freeze-free, 50%
-5 to 0°F (-20.6 to -17.8°C) coldest night
- First snow
- December 5
- Last snow
- March 23
- Winters with snow
- 92%
- Snow per year
- 39"
median, 1991–2020
median, 1991–2020
23 of 25 observed
NOAA normal
Frost risk by date in Mansfield Center
Half of springs at Willimantic Windham Airport, CT see their last 32°F night by April 28; only one in ten is past it by April 17, and one in ten still has one after May 11. Planting tender crops after May 3 leaves a 30% risk of a frost on them, after May 7 20%, and after May 11 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 86% of the 28 Connecticut stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 13 in half of years, as early as October 2 one year in ten, and holds off past October 29 one year in ten. A hard freeze of 28°F follows 12 days later, around October 25; in spring the one-in-ten date for 28°F is April 29, 12 days before the 32°F one. The freeze-free season lasts 167 days in a typical year, shorter than at 75% of the 28 Connecticut stations; it reaches 189 days one year in ten and falls short of 149 one year in ten. On average 135 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 11 days longer, to about May 9, and return around October 3. Severe cold of 16°F or below comes every winter, usually between December 1 and March 13.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 27 | Apr 30 | May 3 | May 6 | May 9 | May 11 | May 14 | May 18 | May 22 |
| 32°F | Apr 17 | Apr 20 | Apr 23 | Apr 26 | Apr 28 | Apr 30 | May 3 | May 7 | May 11 |
| 28°F | Apr 2 | Apr 5 | Apr 9 | Apr 12 | Apr 14 | Apr 17 | Apr 20 | Apr 24 | Apr 29 |
| 24°F | Mar 17 | Mar 24 | Mar 28 | Mar 31 | Apr 2 | Apr 3 | Apr 5 | Apr 9 | Apr 15 |
| 20°F | Mar 7 | Mar 12 | Mar 15 | Mar 18 | Mar 21 | Mar 25 | Mar 28 | Mar 31 | Apr 3 |
| 16°F | Feb 26 | Mar 3 | Mar 7 | Mar 10 | Mar 13 | Mar 16 | Mar 19 | Mar 22 | Mar 27 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 23 | Sep 27 | Sep 29 | Oct 1 | Oct 3 | Oct 5 | Oct 8 | Oct 12 | Oct 16 |
| 32°F | Oct 2 | Oct 5 | Oct 8 | Oct 10 | Oct 13 | Oct 16 | Oct 19 | Oct 24 | Oct 29 |
| 28°F | Oct 10 | Oct 15 | Oct 19 | Oct 23 | Oct 25 | Oct 29 | Nov 1 | Nov 4 | Nov 7 |
| 24°F | Oct 21 | Oct 26 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 12 | Nov 15 | Nov 22 |
| 20°F | Nov 1 | Nov 8 | Nov 12 | Nov 15 | Nov 19 | Nov 22 | Nov 25 | Nov 30 | Dec 5 |
| 16°F | Nov 16 | Nov 21 | Nov 25 | Nov 29 | Dec 1 | Dec 4 | Dec 8 | Dec 13 | Dec 21 |
Freeze probabilities 1991–2020 at Willimantic Windham Airport, CT, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 06250 →Compare Mansfield Center with another place →
Weather by month in Mansfield Center
July is the warmest month at Willimantic Windham Airport, CT, averaging 83°F by day and 62°F at night; January is the coldest at 36°F and 18°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 38% of years.
Warmth for growing adds up to 2,758 growing degree days a year (base 50°F), fewer than at 57% of the 28 Connecticut stations. 31% of them (865) have built up by the end of June, and July adds the most, 693. Precipitation totals 43.5 inches a year, most in August (4.4") and least in February (2.7"); May to September bring 43% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 36 | 18 | 3.2 | 100% | 28 | 0 |
| Feb | 39 | 19 | 2.7 | 100% | 25 | 1 |
| Mar | 47 | 27 | 4.0 | 100% | 23 | 11 |
| Apr | 59 | 37 | 4.0 | 100% | 9 | 69 |
| May | 70 | 47 | 3.4 | 38% | 1 | 273 |
| Jun | 78 | 56 | 3.9 | 0% | 0 | 510 |
| Jul | 83 | 62 | 2.7 | 0% | 0 | 693 |
| Aug | 81 | 60 | 4.4 | 0% | 0 | 640 |
| Sep | 74 | 52 | 4.1 | 6% | <1 | 403 |
| Oct | 63 | 41 | 3.8 | 92% | 6 | 131 |
| Nov | 52 | 31 | 3.6 | 100% | 18 | 23 |
| Dec | 41 | 24 | 3.7 | 100% | 25 | 3 |
Monthly normals 1991–2020 at Willimantic Windham Airport, CT (247 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Storrs, CT, 2 miles northwest of Mansfield Center and 418 feet higher, has a last frost 9 days earlier (April 19), a first frost 9 days later (October 22), a season 19 days longer.
When it snows in Mansfield Center, Connecticut
The first measurable snow (0.1 inch or more) in Mansfield Center usually arrives around December 5, and the last of the season around March 23. Those are the middle dates across the winters of 1991–2020 at Storrs, CT, 2.4 miles away: half of years saw snow earlier, half later. Snow fell in 92% of those winters. The last 32°F night of spring typically comes 36 days after the last snow.
Planting calendar for 06250
| When | What to do |
|---|---|
| February 17 – March 3 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 3 – March 17 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 31 – April 14 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 28 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 21 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 29 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 13 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 06250 is 2 miles from Willimantic Windham Airport, CT, which stands at 247 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 06226 (Willimantic). The 2023 USDA Plant Hardiness Zone Map lists ZIP 06250 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across Connecticut →
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.