Everett Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Boston Logan Intl AP. A median date has an even chance of a later freeze in spring, or an earlier one in fall.
The last spring freeze typically comes around April 4 and the first fall freeze around November 9, a growing season of about 218 days.
- Median at 36°F
- last April 17, first October 29
- Median at 32°F
- last April 4, first November 9
- Median at 28°F
- last March 28, first November 21
Last freeze in spring
The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 1 | Apr 26 | Apr 22 | Apr 19 | Apr 17 | Apr 15 | Apr 12 | Apr 9 | Apr 6 |
| 32°F | Apr 17 | Apr 11 | Apr 8 | Apr 6 | Apr 4 | Apr 3 | Apr 1 | Mar 30 | Mar 25 |
| 28°F | Apr 6 | Apr 3 | Apr 1 | Mar 30 | Mar 28 | Mar 25 | Mar 22 | Mar 19 | Mar 15 |
| 24°F | Apr 1 | Mar 28 | Mar 24 | Mar 21 | Mar 19 | Mar 16 | Mar 13 | Mar 10 | Mar 6 |
| 20°F | Mar 25 | Mar 20 | Mar 17 | Mar 14 | Mar 11 | Mar 8 | Mar 5 | Mar 2 | Feb 24 |
| 16°F | Mar 19 | Mar 13 | Mar 8 | Mar 5 | Mar 2 | Feb 27 | Feb 23 | Feb 16 | Feb 9 |
First freeze in fall
The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 15 | Oct 20 | Oct 24 | Oct 26 | Oct 29 | Nov 1 | Nov 2 | Nov 5 | Nov 11 |
| 32°F | Oct 29 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 12 | Nov 14 | Nov 17 | Nov 22 |
| 28°F | Nov 8 | Nov 12 | Nov 15 | Nov 18 | Nov 21 | Nov 24 | Nov 27 | Dec 1 | Dec 5 |
| 24°F | Nov 16 | Nov 22 | Nov 26 | Nov 29 | Dec 1 | Dec 4 | Dec 7 | Dec 11 | Dec 18 |
| 20°F | Nov 27 | Dec 1 | Dec 4 | Dec 8 | Dec 11 | Dec 16 | Dec 19 | Dec 24 | Jan 1 |
| 16°F | Dec 6 | Dec 11 | Dec 16 | Dec 19 | Dec 23 | Dec 26 | Dec 31 | Jan 4 | Jan 12 |
Growing season length
Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.
| Threshold | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | 210 | 205 | 201 | 197 | 194 | 190 | 186 | 181 | 175 |
| 32°F | 235 | 230 | 225 | 221 | 218 | 214 | 211 | 207 | 201 |
| 28°F | 258 | 252 | 247 | 243 | 239 | 236 | 232 | 227 | 221 |
| 24°F | 278 | 271 | 266 | 262 | 258 | 254 | 250 | 245 | 239 |
| 20°F | 298 | 290 | 284 | 280 | 275 | 271 | 267 | 262 | 255 |
| 16°F | 318 | 309 | 304 | 299 | 294 | 290 | 285 | 279 | 273 |
How often it gets that cold
The share of years with at least one night at or below each temperature.
- 36°F or colder
- 100% of years
- 32°F or colder
- 100% of years
- 28°F or colder
- 100% of years
- 24°F or colder
- 100% of years
- 20°F or colder
- 100% of years
- 16°F or colder
- 100% of years
Degree days
A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.
- Heating degree days, base 65°F
- 5,545
- Cooling degree days, base 65°F
- 802
- Growing degree days, base 40°F
- 5,333
- Growing degree days, base 45°F
- 4,109
- Growing degree days, base 50°F
- 3,050
- Growing degree days, base 55°F
- 2,145
- Growing degree days, base 60°F
- 1,399
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,086 | 0 | 2 |
| February | 930 | 0 | 1 |
| March | 828 | 1 | 12 |
| April | 496 | 4 | 78 |
| May | 234 | 29 | 271 |
| June | 50 | 138 | 539 |
| July | 4 | 284 | 745 |
| August | 5 | 245 | 705 |
| September | 71 | 91 | 470 |
| October | 326 | 9 | 183 |
| November | 608 | 0 | 38 |
| December | 908 | 0 | 5 |
What this means
NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.
The station is 6.4 km from Everett. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.
More
Sources
NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00014739 (Boston Logan Intl AP). Public domain.