Tangent Frost Dates and Growing Season
Frost and the growing season
NOAA's 1991-2020 freeze probabilities for Corvallis State Univ. 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 17 and the first fall freeze around October 28, a growing season of about 194 days.
- Median at 36°F
- last May 11, first October 10
- Median at 32°F
- last April 17, first October 28
- Median at 28°F
- last March 1, first November 17
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 | Jun 2 | May 25 | May 20 | May 15 | May 11 | May 7 | May 3 | Apr 29 | Apr 25 |
| 32°F | May 8 | May 1 | Apr 27 | Apr 23 | Apr 17 | Apr 12 | Apr 6 | Mar 31 | Mar 22 |
| 28°F | Apr 5 | Mar 26 | Mar 16 | Mar 8 | Mar 1 | Feb 26 | Feb 19 | Feb 13 | Jan 25 |
| 24°F | Feb 24 | Feb 18 | Feb 11 | Feb 1 | Jan 24 | Jan 13 | Jan 3 | Dec 26 | Dec 10 |
| 20°F | Feb 11 | Jan 30 | Jan 16 | Jan 7 | Dec 31 | Dec 25 | Dec 17 | Dec 11 | Dec 2 |
| 16°F | Feb 4 | Jan 14 | Jan 1 | Dec 30 | Dec 23 | Dec 16 | Dec 13 | Dec 7 | Dec 4 |
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 23 | Sep 30 | Oct 2 | Oct 6 | Oct 10 | Oct 14 | Oct 17 | Oct 23 | Oct 28 |
| 32°F | Oct 5 | Oct 14 | Oct 20 | Oct 25 | Oct 28 | Nov 1 | Nov 4 | Nov 10 | Nov 19 |
| 28°F | Oct 22 | Nov 1 | Nov 5 | Nov 12 | Nov 17 | Nov 23 | Nov 30 | Dec 6 | Dec 18 |
| 24°F | Nov 7 | Nov 16 | Nov 24 | Nov 30 | Dec 5 | Dec 11 | Dec 22 | Dec 30 | Jan 13 |
| 20°F | Nov 20 | Nov 30 | Dec 6 | Dec 11 | Dec 19 | Dec 24 | Dec 30 | Jan 9 | Jan 24 |
| 16°F | Dec 1 | Dec 5 | Dec 8 | Dec 12 | Dec 18 | Dec 23 | Dec 29 | Jan 1 | Jan 26 |
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 | 176 | 168 | 162 | 157 | 151 | 146 | 140 | 133 | 122 |
| 32°F | 227 | 215 | 207 | 200 | 194 | 188 | 182 | 174 | 163 |
| 28°F | 301 | 286 | 275 | 267 | 259 | 250 | 240 | 230 | 216 |
| 24°F | 362 | 347 | 337 | 327 | 318 | 310 | 300 | 289 | 273 |
| 20°F | 365 | 365 | 365 | 365 | 360 | 348 | 339 | 330 | 317 |
| 16°F | 365 | 365 | 365 | 365 | 365 | 365 | 365 | 358 | 339 |
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
- 91% of years
- 20°F or colder
- 55% of years
- 16°F or colder
- 23% 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
- 4,670
- Cooling degree days, base 65°F
- 291
- Growing degree days, base 40°F
- 4,924
- Growing degree days, base 45°F
- 3,450
- Growing degree days, base 50°F
- 2,278
- Growing degree days, base 55°F
- 1,383
- Growing degree days, base 60°F
- 724
Growing degree days by month, base 50°F
Heating and cooling by month
| Month | Heating DD | Cooling DD | Growing DD 50 |
|---|---|---|---|
| January | 749 | 0 | 4 |
| February | 615 | 0 | 6 |
| March | 572 | 0 | 23 |
| April | 444 | 0 | 67 |
| May | 276 | 6 | 206 |
| June | 142 | 28 | 337 |
| July | 30 | 107 | 542 |
| August | 28 | 107 | 544 |
| September | 104 | 41 | 387 |
| October | 358 | 1 | 137 |
| November | 588 | 0 | 21 |
| December | 766 | 0 | 4 |
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 12.2 km from Tangent. 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 USC00351862 (Corvallis State Univ). Public domain.