Leesburg Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Warsaw. 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 28 and the first fall freeze around October 18, a growing season of about 170 days.
- Median at 36°F
- last May 9, first October 5
- Median at 32°F
- last April 28, first October 18
- Median at 28°F
- last April 16, first October 30
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 25 | May 19 | May 15 | May 12 | May 9 | May 6 | May 2 | Apr 29 | Apr 23 |
| 32°F | May 14 | May 8 | May 4 | May 1 | Apr 28 | Apr 24 | Apr 21 | Apr 18 | Apr 13 |
| 28°F | May 4 | Apr 29 | Apr 23 | Apr 20 | Apr 16 | Apr 13 | Apr 9 | Apr 5 | Apr 1 |
| 24°F | Apr 20 | Apr 14 | Apr 9 | Apr 6 | Apr 4 | Apr 1 | Mar 30 | Mar 26 | Mar 21 |
| 20°F | Apr 8 | Apr 2 | Mar 31 | Mar 28 | Mar 25 | Mar 22 | Mar 18 | Mar 15 | Mar 9 |
| 16°F | Mar 30 | Mar 25 | Mar 22 | Mar 18 | Mar 15 | Mar 12 | Mar 8 | Mar 4 | Feb 28 |
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 20 | Sep 25 | Sep 29 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 15 | Oct 20 |
| 32°F | Oct 1 | Oct 7 | Oct 12 | Oct 15 | Oct 18 | Oct 21 | Oct 23 | Oct 26 | Oct 30 |
| 28°F | Oct 17 | Oct 21 | Oct 25 | Oct 28 | Oct 30 | Nov 1 | Nov 3 | Nov 7 | Nov 12 |
| 24°F | Nov 1 | Nov 2 | Nov 4 | Nov 6 | Nov 10 | Nov 13 | Nov 16 | Nov 20 | Nov 26 |
| 20°F | Nov 6 | Nov 10 | Nov 14 | Nov 17 | Nov 21 | Nov 24 | Nov 28 | Dec 2 | Dec 9 |
| 16°F | Nov 14 | Nov 19 | Nov 25 | Nov 29 | Dec 2 | Dec 5 | Dec 10 | Dec 16 | Dec 24 |
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 | 168 | 161 | 156 | 152 | 148 | 145 | 140 | 135 | 128 |
| 32°F | 191 | 184 | 179 | 174 | 170 | 166 | 161 | 155 | 149 |
| 28°F | 217 | 210 | 205 | 200 | 195 | 191 | 187 | 181 | 174 |
| 24°F | 243 | 235 | 230 | 226 | 221 | 217 | 213 | 206 | 198 |
| 20°F | 266 | 258 | 252 | 246 | 242 | 237 | 233 | 228 | 220 |
| 16°F | 289 | 280 | 273 | 269 | 264 | 258 | 253 | 246 | 238 |
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
- 6,178
- Cooling degree days, base 65°F
- 761
- Growing degree days, base 40°F
- 5,197
- Growing degree days, base 45°F
- 4,039
- Growing degree days, base 50°F
- 3,023
- Growing degree days, base 55°F
- 2,134
- Growing degree days, base 60°F
- 1,378
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 1,246 | 0 | 1 |
| February | 1,040 | 0 | 2 |
| March | 848 | 2 | 27 |
| April | 475 | 7 | 107 |
| May | 203 | 54 | 331 |
| June | 33 | 168 | 585 |
| July | 6 | 246 | 705 |
| August | 11 | 191 | 645 |
| September | 105 | 84 | 432 |
| October | 395 | 10 | 160 |
| November | 732 | 0 | 26 |
| December | 1,085 | 0 | 3 |
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 7.8 km from Leesburg. 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 USC00129240 (Warsaw). Public domain.