Cairo climate

Cairo Frost Dates and Growing Season

NOAA 1991-2020 normals for E Jewett, 14 km from Cairo, elevation 1991 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for E Jewett. 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 May 20 and the first fall freeze around September 27, a growing season of about 129 days.

Median at 36°F
last June 2, first September 15
Median at 32°F
last May 20, first September 27
Median at 28°F
last May 5, first October 7

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°FJun 15Jun 10Jun 7Jun 4Jun 2May 31May 28May 25May 19
32°FJun 2May 29May 25May 23May 20May 16May 13May 9May 4
28°FMay 20May 15May 11May 8May 5May 2Apr 30Apr 26Apr 21
24°FMay 7May 1Apr 28Apr 25Apr 22Apr 19Apr 17Apr 12Apr 8
20°FApr 23Apr 19Apr 15Apr 12Apr 9Apr 7Apr 5Apr 3Mar 30
16°FApr 12Apr 8Apr 6Apr 4Apr 2Mar 31Mar 29Mar 24Mar 20

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°FAug 31Sep 5Sep 9Sep 12Sep 15Sep 18Sep 21Sep 25Sep 29
32°FSep 13Sep 18Sep 21Sep 24Sep 27Sep 30Oct 2Oct 5Oct 9
28°FSep 24Sep 29Oct 1Oct 4Oct 7Oct 10Oct 14Oct 18Oct 25
24°FOct 3Oct 10Oct 14Oct 19Oct 23Oct 27Oct 31Nov 3Nov 8
20°FOct 16Oct 26Oct 30Nov 2Nov 5Nov 9Nov 12Nov 16Nov 21
16°FNov 3Nov 9Nov 12Nov 15Nov 18Nov 21Nov 25Nov 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°F124118113109104101969184
32°F150143139134129125121116109
28°F176170165160156151147142133
24°F204197192187183178174167158
20°F229223217212209205200194186
16°F250243238234230226222217210

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
7,957
Cooling degree days, base 65°F
172
Growing degree days, base 40°F
3,519
Growing degree days, base 45°F
2,537
Growing degree days, base 50°F
1,700
Growing degree days, base 55°F
1,016
Growing degree days, base 60°F
498

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,36701
February1,19100
March1,10502
April711025
May3937143
June15033337
July6071476
August8946422
September25714228
October579157
November86409
December1,19001

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 14 km from Cairo. 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 USC00302366 (E Jewett). Public domain.