Spring Green climate

Spring Green Frost Dates and Growing Season

NOAA 1991-2020 normals for Lone Rock Tri CO AP, 10.1 km from Spring Green, elevation 717 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lone Rock Tri CO AP. 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 30 and the first fall freeze around October 9, a growing season of about 161 days.

Median at 36°F
last May 9, first September 30
Median at 32°F
last April 30, first October 9
Median at 28°F
last April 19, first October 18

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 23May 19May 15May 12May 9May 6May 3Apr 30Apr 25
32°FMay 14May 9May 6May 2Apr 30Apr 26Apr 23Apr 20Apr 15
28°FMay 5Apr 30Apr 25Apr 22Apr 19Apr 16Apr 13Apr 10Apr 5
24°FApr 24Apr 18Apr 14Apr 11Apr 8Apr 5Apr 2Mar 31Mar 23
20°FApr 12Apr 7Apr 3Apr 1Mar 30Mar 26Mar 21Mar 17Mar 12
16°FApr 2Mar 29Mar 25Mar 21Mar 18Mar 15Mar 12Mar 7Mar 3

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°FSep 17Sep 21Sep 25Sep 28Sep 30Oct 2Oct 5Oct 8Oct 12
32°FSep 25Sep 30Oct 3Oct 6Oct 9Oct 12Oct 14Oct 16Oct 21
28°FOct 4Oct 10Oct 13Oct 16Oct 18Oct 21Oct 24Oct 27Oct 31
24°FOct 15Oct 20Oct 23Oct 26Oct 29Oct 31Nov 3Nov 6Nov 11
20°FOct 26Oct 31Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 24
16°FNov 4Nov 8Nov 12Nov 15Nov 18Nov 21Nov 24Nov 29Dec 3

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°F160154150146143139135130123
32°F181173168164161157153149142
28°F202195189185180177172166160
24°F225217211208204199195189181
20°F249241236231226221217212204
16°F268260254250245241237231225

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
7,066
Cooling degree days, base 65°F
647
Growing degree days, base 40°F
4,772
Growing degree days, base 45°F
3,696
Growing degree days, base 50°F
2,745
Growing degree days, base 55°F
1,917
Growing degree days, base 60°F
1,211

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,43500
February1,17601
March915118
April533276
May22342301
June35143558
July7224682
August19169615
September14458372
October4837110
November848012
December1,24901

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 10.1 km from Spring Green. 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 USW00014921 (Lone Rock Tri CO AP). Public domain.