Bettsville Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Fremont Ag Stn. 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 21 and the first fall freeze around October 24, a growing season of about 183 days.
- Median at 36°F
- last May 1, first October 10
- Median at 32°F
- last April 21, first October 24
- Median at 28°F
- last April 8, first November 3
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 17 | May 11 | May 7 | May 4 | May 1 | Apr 29 | Apr 26 | Apr 23 | Apr 18 |
| 32°F | May 6 | Apr 30 | Apr 27 | Apr 24 | Apr 21 | Apr 18 | Apr 15 | Apr 12 | Apr 8 |
| 28°F | Apr 22 | Apr 18 | Apr 15 | Apr 11 | Apr 8 | Apr 5 | Apr 3 | Apr 1 | Mar 26 |
| 24°F | Apr 11 | Apr 5 | Apr 3 | Apr 1 | Mar 30 | Mar 27 | Mar 23 | Mar 19 | Mar 15 |
| 20°F | Apr 1 | Mar 29 | Mar 25 | Mar 22 | Mar 19 | Mar 16 | Mar 13 | Mar 9 | Mar 4 |
| 16°F | Mar 27 | Mar 21 | Mar 17 | Mar 14 | Mar 10 | Mar 7 | Mar 3 | Feb 27 | Feb 20 |
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 | Sep 26 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 13 | Oct 17 | Oct 20 | Oct 26 |
| 32°F | Oct 8 | Oct 13 | Oct 17 | Oct 21 | Oct 24 | Oct 28 | Oct 31 | Nov 2 | Nov 6 |
| 28°F | Oct 21 | Oct 27 | Oct 31 | Nov 1 | Nov 3 | Nov 6 | Nov 10 | Nov 14 | Nov 19 |
| 24°F | Nov 1 | Nov 5 | Nov 9 | Nov 13 | Nov 16 | Nov 19 | Nov 23 | Nov 26 | Dec 1 |
| 20°F | Nov 10 | Nov 16 | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 4 | Dec 8 | Dec 16 |
| 16°F | Nov 22 | Nov 28 | Dec 1 | Dec 5 | Dec 8 | Dec 13 | Dec 17 | Dec 23 | Dec 27 |
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 | 181 | 174 | 169 | 165 | 160 | 156 | 151 | 147 | 140 |
| 32°F | 205 | 197 | 192 | 188 | 183 | 180 | 175 | 171 | 163 |
| 28°F | 228 | 222 | 218 | 214 | 210 | 206 | 201 | 196 | 188 |
| 24°F | 255 | 246 | 240 | 236 | 232 | 228 | 224 | 220 | 213 |
| 20°F | 279 | 270 | 263 | 258 | 254 | 249 | 245 | 240 | 232 |
| 16°F | 301 | 291 | 284 | 280 | 275 | 270 | 265 | 259 | 251 |
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
- 5,949
- Cooling degree days, base 65°F
- 838
- Growing degree days, base 40°F
- 5,349
- Growing degree days, base 45°F
- 4,175
- Growing degree days, base 50°F
- 3,141
- Growing degree days, base 55°F
- 2,236
- Growing degree days, base 60°F
- 1,466
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,185 | 0 | 1 |
| February | 1,008 | 0 | 2 |
| March | 848 | 2 | 31 |
| April | 479 | 8 | 110 |
| May | 192 | 60 | 344 |
| June | 33 | 192 | 609 |
| July | 4 | 275 | 736 |
| August | 11 | 208 | 662 |
| September | 94 | 79 | 438 |
| October | 378 | 16 | 170 |
| November | 692 | 0 | 32 |
| December | 1,026 | 0 | 6 |
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 9.1 km from Bettsville. 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 USC00332976 (Fremont Ag Stn). Public domain.