Luray Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Luray 5 E. 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 23 and the first fall freeze around October 22, a growing season of about 179 days.
- Median at 36°F
- last May 7, first October 11
- Median at 32°F
- last April 23, first October 22
- Median at 28°F
- last April 8, first October 31
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 24 | May 20 | May 16 | May 11 | May 7 | May 3 | Apr 30 | Apr 26 | Apr 21 |
| 32°F | May 15 | May 6 | May 1 | Apr 27 | Apr 23 | Apr 20 | Apr 16 | Apr 13 | Apr 7 |
| 28°F | Apr 29 | Apr 21 | Apr 16 | Apr 12 | Apr 8 | Apr 5 | Apr 2 | Mar 31 | Mar 27 |
| 24°F | Apr 11 | Apr 5 | Apr 2 | Mar 31 | Mar 27 | Mar 24 | Mar 20 | Mar 16 | Mar 10 |
| 20°F | Mar 31 | Mar 27 | Mar 23 | Mar 19 | Mar 16 | Mar 13 | Mar 9 | Mar 3 | Feb 26 |
| 16°F | Mar 22 | Mar 17 | Mar 14 | Mar 10 | Mar 6 | Mar 2 | Feb 27 | Feb 22 | Feb 13 |
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 28 | Oct 2 | Oct 5 | Oct 7 | Oct 11 | Oct 14 | Oct 16 | Oct 20 | Oct 24 |
| 32°F | Oct 6 | Oct 11 | Oct 15 | Oct 19 | Oct 22 | Oct 24 | Oct 27 | Oct 30 | Nov 2 |
| 28°F | Oct 15 | Oct 22 | Oct 25 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 12 |
| 24°F | Oct 28 | Nov 1 | Nov 4 | Nov 7 | Nov 11 | Nov 14 | Nov 17 | Nov 22 | Nov 30 |
| 20°F | Nov 7 | Nov 12 | Nov 17 | Nov 20 | Nov 25 | Nov 30 | Dec 2 | Dec 7 | Dec 17 |
| 16°F | Nov 19 | Nov 26 | Dec 1 | Dec 5 | Dec 9 | Dec 15 | Dec 22 | Dec 27 | Jan 4 |
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 | 175 | 169 | 164 | 160 | 155 | 151 | 147 | 141 | 135 |
| 32°F | 200 | 194 | 188 | 183 | 179 | 173 | 168 | 162 | 154 |
| 28°F | 226 | 219 | 213 | 208 | 204 | 200 | 195 | 189 | 181 |
| 24°F | 255 | 246 | 240 | 235 | 231 | 226 | 221 | 215 | 208 |
| 20°F | 284 | 274 | 267 | 261 | 256 | 250 | 245 | 238 | 229 |
| 16°F | 309 | 299 | 293 | 287 | 281 | 275 | 269 | 262 | 252 |
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
- 4,825
- Cooling degree days, base 65°F
- 856
- Growing degree days, base 40°F
- 5,893
- Growing degree days, base 45°F
- 4,573
- Growing degree days, base 50°F
- 3,406
- Growing degree days, base 55°F
- 2,397
- Growing degree days, base 60°F
- 1,546
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 987 | 0 | 9 |
| February | 798 | 0 | 12 |
| March | 677 | 1 | 50 |
| April | 351 | 13 | 178 |
| May | 149 | 58 | 379 |
| June | 26 | 165 | 589 |
| July | 2 | 272 | 735 |
| August | 6 | 228 | 687 |
| September | 69 | 102 | 484 |
| October | 315 | 17 | 208 |
| November | 590 | 1 | 57 |
| December | 856 | 0 | 18 |
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 7.5 km from Luray. 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 USC00445096 (Luray 5 E). Public domain.