Thomson climate

Thomson Frost Dates and Growing Season

NOAA 1991-2020 normals for Fulton L&d #13, 8.2 km from Thomson, elevation 592 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Fulton L&d #13. 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 13 and the first fall freeze around October 26, a growing season of about 195 days.

Median at 36°F
last April 24, first October 16
Median at 32°F
last April 13, first October 26
Median at 28°F
last April 4, 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.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 9May 4Apr 30Apr 28Apr 24Apr 21Apr 17Apr 14Apr 9
32°FApr 28Apr 23Apr 18Apr 16Apr 13Apr 9Apr 6Apr 4Apr 1
28°FApr 18Apr 13Apr 9Apr 6Apr 4Apr 2Mar 30Mar 25Mar 19
24°FApr 10Apr 5Apr 2Mar 30Mar 26Mar 22Mar 19Mar 15Mar 10
20°FApr 2Mar 28Mar 24Mar 20Mar 16Mar 14Mar 11Mar 8Mar 3
16°FMar 24Mar 19Mar 15Mar 13Mar 10Mar 7Mar 5Mar 2Feb 27

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.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 1Oct 7Oct 11Oct 14Oct 16Oct 19Oct 21Oct 24Oct 28
32°FOct 13Oct 18Oct 21Oct 24Oct 26Oct 28Oct 31Nov 2Nov 7
28°FOct 23Oct 28Oct 31Nov 1Nov 3Nov 6Nov 10Nov 14Nov 19
24°FOct 31Nov 3Nov 7Nov 10Nov 14Nov 17Nov 21Nov 24Nov 29
20°FNov 5Nov 12Nov 16Nov 19Nov 23Nov 26Nov 29Dec 2Dec 8
16°FNov 13Nov 20Nov 25Nov 28Dec 1Dec 3Dec 7Dec 11Dec 18

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.

Threshold10%20%30%40%50%60%70%80%90%
36°F193186182178174170166161155
32°F215207203198195191186180174
28°F235228222218214211206202196
24°F254247242238234229225220213
20°F269262258254250246241235228
16°F285278273268264261256252244

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
6,394
Cooling degree days, base 65°F
937
Growing degree days, base 40°F
5,399
Growing degree days, base 45°F
4,261
Growing degree days, base 50°F
3,245
Growing degree days, base 55°F
2,348
Growing degree days, base 60°F
1,580

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,35000
February1,10701
March871120
April4686106
May17559357
June25211636
July3300763
August6243702
September88105469
October37812168
November765023
December1,15802

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 8.2 km from Thomson. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00113290 (Fulton L&d #13). Public domain.