Republic County climate

Republic County Frost Dates and Growing Season

NOAA 1991-2020 normals for Belleville, 1.5 km from Republic County, elevation 1530 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Belleville. 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 22 and the first fall freeze around October 17, a growing season of about 175 days.

Median at 36°F
last April 30, first October 7
Median at 32°F
last April 22, first October 17
Median at 28°F
last April 12, first October 26

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 12May 8May 5May 2Apr 30Apr 29Apr 26Apr 23Apr 19
32°FMay 5May 1Apr 28Apr 25Apr 22Apr 20Apr 17Apr 13Apr 8
28°FApr 27Apr 22Apr 19Apr 16Apr 12Apr 9Apr 6Apr 3Mar 28
24°FApr 19Apr 13Apr 8Apr 5Apr 2Mar 31Mar 27Mar 23Mar 16
20°FApr 10Apr 4Mar 31Mar 28Mar 24Mar 20Mar 16Mar 13Mar 7
16°FApr 1Mar 26Mar 21Mar 17Mar 13Mar 10Mar 7Mar 3Feb 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°FSep 24Sep 30Oct 2Oct 5Oct 7Oct 10Oct 13Oct 16Oct 20
32°FSep 30Oct 5Oct 10Oct 14Oct 17Oct 19Oct 21Oct 24Oct 29
28°FOct 10Oct 17Oct 20Oct 23Oct 26Oct 28Nov 1Nov 3Nov 7
24°FOct 21Oct 25Oct 29Nov 1Nov 3Nov 6Nov 8Nov 11Nov 16
20°FOct 28Nov 2Nov 5Nov 8Nov 11Nov 13Nov 16Nov 21Nov 27
16°FNov 4Nov 9Nov 12Nov 16Nov 19Nov 23Nov 26Dec 1Dec 7

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°F176170166162158155151147140
32°F193187182178175171166162154
28°F216209203199195191186181174
24°F236227222218214210204199191
20°F255247241236231227222216209
16°F272265259254249244240234226

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
5,723
Cooling degree days, base 65°F
1,287
Growing degree days, base 40°F
6,041
Growing degree days, base 45°F
4,835
Growing degree days, base 50°F
3,760
Growing degree days, base 55°F
2,809
Growing degree days, base 60°F
1,985

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,19300
February96905
March733146
April4119145
May14979404
June12271709
July1417882
August3339801
September71149531
October35320203
November734031
December1,09401

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 1.5 km from Republic County. 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 USC00140682 (Belleville). Public domain.