Batavia climate

Batavia Frost Dates and Growing Season

NOAA 1991-2020 normals for Fairfield, 18 km from Batavia, elevation 740 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Fairfield. 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 27 and the first fall freeze around October 12, a growing season of about 168 days.

Median at 36°F
last May 8, first October 3
Median at 32°F
last April 27, first October 12
Median at 28°F
last April 15, first October 22

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

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°F169161156152148144139133127
32°F188182177172168164159155145
28°F210204199195190185180175166
24°F233225220215211207202198190
20°F255247241235231226221216209
16°F274266260255251246241236230

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
6,377
Cooling degree days, base 65°F
842
Growing degree days, base 40°F
5,307
Growing degree days, base 45°F
4,164
Growing degree days, base 50°F
3,143
Growing degree days, base 55°F
2,244
Growing degree days, base 60°F
1,473

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33000
February1,07402
March829133
April4478125
May18951341
June26176600
July4278739
August11226680
September10791438
October41311158
November788026
December1,16102

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 18 km from Batavia. 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 USC00132789 (Fairfield). Public domain.