Bureau County climate

Bureau County Frost Dates and Growing Season

NOAA 1991-2020 normals for Princeton, 7.7 km from Bureau County, elevation 697 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Princeton. 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 177 days.

Median at 36°F
last May 3, first October 6
Median at 32°F
last April 22, first October 17
Median at 28°F
last April 12, first October 27

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

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°F173167163158155151148143135
32°F194188184180177172168163156
28°F216210205201197193189185178
24°F238231225222218214210205198
20°F260253247242238233229224217
16°F279271265260256252247242233

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
6,401
Cooling degree days, base 65°F
860
Growing degree days, base 40°F
5,297
Growing degree days, base 45°F
4,163
Growing degree days, base 50°F
3,152
Growing degree days, base 55°F
2,261
Growing degree days, base 60°F
1,493

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33100
February1,08401
March847229
April4648114
May18163358
June24192618
July4278739
August10217673
September10289440
October40711156
November786023
December1,16202

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 7.7 km from Bureau 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 USC00116998 (Princeton). Public domain.