Fairbury climate

Fairbury Frost Dates and Growing Season

NOAA 1991-2020 normals for Fairbury 5S, 7.1 km from Fairbury, elevation 1350 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Fairbury 5S. 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 25 and the first fall freeze around October 15, a growing season of about 169 days.

Median at 36°F
last May 3, first October 5
Median at 32°F
last April 25, first October 15
Median at 28°F
last April 14, first October 24

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 17May 12May 8May 6May 3May 1Apr 30Apr 26Apr 20
32°FMay 7May 3Apr 30Apr 28Apr 25Apr 21Apr 18Apr 15Apr 9
28°FApr 30Apr 25Apr 21Apr 18Apr 14Apr 11Apr 7Apr 4Mar 31
24°FApr 20Apr 15Apr 10Apr 7Apr 3Apr 1Mar 29Mar 24Mar 17
20°FApr 13Apr 5Apr 1Mar 30Mar 26Mar 21Mar 17Mar 12Mar 7
16°FApr 3Mar 29Mar 23Mar 19Mar 15Mar 11Mar 8Mar 4Feb 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 22Sep 27Sep 30Oct 2Oct 5Oct 8Oct 11Oct 13Oct 17
32°FSep 30Oct 5Oct 9Oct 13Oct 15Oct 17Oct 20Oct 22Oct 26
28°FOct 10Oct 16Oct 19Oct 22Oct 24Oct 27Oct 29Nov 1Nov 5
24°FOct 19Oct 23Oct 26Oct 30Nov 1Nov 3Nov 6Nov 10Nov 15
20°FOct 25Oct 31Nov 2Nov 5Nov 8Nov 11Nov 15Nov 19Nov 25
16°FNov 1Nov 6Nov 10Nov 14Nov 17Nov 22Nov 26Dec 1Dec 6

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°F170164159156152149145140134
32°F188182177173169166161157150
28°F212203198194190185181177168
24°F232223217213209204200195188
20°F251243236232227222218214205
16°F273264257250246241236230221

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
5,966
Cooling degree days, base 65°F
1,102
Growing degree days, base 40°F
5,737
Growing degree days, base 45°F
4,554
Growing degree days, base 50°F
3,501
Growing degree days, base 55°F
2,572
Growing degree days, base 60°F
1,770

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,23700
February99705
March767141
April4378133
May17363367
June19226657
July3362824
August6299758
September87128494
October37116191
November755031
December1,11601

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 7.1 km from Fairbury. 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 USC00252820 (Fairbury 5S). Public domain.