Sigourney climate

Sigourney Frost Dates and Growing Season

NOAA 1991-2020 normals for Sigourney, 2 km from Sigourney, elevation 732 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sigourney. 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 24 and the first fall freeze around October 15, a growing season of about 172 days.

Median at 36°F
last May 4, first October 5
Median at 32°F
last April 24, first October 15
Median at 28°F
last April 12, 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 9May 7May 4May 2Apr 30Apr 26Apr 20
32°FMay 9May 4May 1Apr 28Apr 24Apr 21Apr 18Apr 14Apr 9
28°FApr 30Apr 24Apr 19Apr 15Apr 12Apr 9Apr 6Apr 3Mar 31
24°FApr 21Apr 13Apr 9Apr 6Apr 3Apr 1Mar 30Mar 24Mar 18
20°FApr 10Apr 4Mar 31Mar 29Mar 25Mar 22Mar 18Mar 13Mar 7
16°FMar 31Mar 26Mar 23Mar 19Mar 15Mar 12Mar 8Mar 5Mar 1

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 21Sep 26Sep 29Oct 2Oct 5Oct 7Oct 10Oct 13Oct 17
32°FSep 30Oct 5Oct 9Oct 12Oct 15Oct 17Oct 20Oct 23Oct 27
28°FOct 12Oct 16Oct 20Oct 22Oct 24Oct 26Oct 29Nov 1Nov 4
24°FOct 21Oct 25Oct 28Oct 30Nov 1Nov 4Nov 7Nov 10Nov 15
20°FOct 31Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 22Nov 27
16°FNov 5Nov 10Nov 14Nov 17Nov 21Nov 24Nov 28Dec 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°F169164159155151148144140135
32°F191186181176172168164159152
28°F211205201197194190184179172
24°F231224219215212208204199192
20°F253245239235231227222217209
16°F272264259254250245240235227

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
6,641
Cooling degree days, base 65°F
806
Growing degree days, base 40°F
5,170
Growing degree days, base 45°F
4,048
Growing degree days, base 50°F
3,046
Growing degree days, base 55°F
2,169
Growing degree days, base 60°F
1,419

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,37500
February1,12402
March871126
April4865101
May19945326
June27173596
July3272733
August11215670
September11485426
October42610146
November812021
December1,19401

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 2 km from Sigourney. 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 USC00137678 (Sigourney). Public domain.