Geneva climate

Geneva Frost Dates and Growing Season

NOAA 1991-2020 normals for Geneva, 0.5 km from Geneva, elevation 1630 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Geneva. 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 20 and the first fall freeze around October 18, a growing season of about 178 days.

Median at 36°F
last April 30, first October 9
Median at 32°F
last April 20, first October 18
Median at 28°F
last April 11, 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 11May 8May 5May 2Apr 30Apr 28Apr 25Apr 21Apr 17
32°FMay 3Apr 30Apr 27Apr 23Apr 20Apr 17Apr 14Apr 11Apr 6
28°FApr 23Apr 19Apr 16Apr 13Apr 11Apr 8Apr 4Apr 1Mar 28
24°FApr 17Apr 12Apr 8Apr 4Apr 1Mar 30Mar 26Mar 21Mar 15
20°FApr 8Apr 3Mar 31Mar 28Mar 24Mar 19Mar 16Mar 11Mar 6
16°FMar 31Mar 26Mar 20Mar 16Mar 13Mar 9Mar 6Mar 3Feb 26

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 26Sep 30Oct 3Oct 6Oct 9Oct 12Oct 15Oct 17Oct 21
32°FOct 2Oct 8Oct 12Oct 16Oct 18Oct 21Oct 23Oct 26Oct 30
28°FOct 11Oct 18Oct 22Oct 24Oct 27Oct 30Nov 2Nov 5Nov 9
24°FOct 21Oct 27Oct 31Nov 3Nov 5Nov 7Nov 10Nov 14Nov 19
20°FOct 29Nov 3Nov 7Nov 10Nov 13Nov 16Nov 19Nov 23Nov 28
16°FNov 5Nov 11Nov 14Nov 18Nov 22Nov 24Nov 28Dec 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°F178172168164160157153149142
32°F197191187183178175170165159
28°F218211206202198194190186178
24°F238230225220216212208203195
20°F257249244239234230224218211
16°F276268263257252247243237228

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
5,637
Cooling degree days, base 65°F
1,127
Growing degree days, base 40°F
5,939
Growing degree days, base 45°F
4,718
Growing degree days, base 50°F
3,625
Growing degree days, base 55°F
2,660
Growing degree days, base 60°F
1,825

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,18700
February95605
March718149
April38511161
May14475404
June14245681
July2349812
August4289750
September70136518
October34019211
November729033
December1,08802

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 0.5 km from Geneva. 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 USC00253175 (Geneva). Public domain.