Byron climate

Byron Frost Dates and Growing Season

NOAA 1991-2020 normals for Tracy Pumping Plt, 9.3 km from Byron, elevation 61 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tracy Pumping Plt. 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 January 19 and the first fall freeze around December 10, a growing season of about 330 days.

Median at 36°F
last February 21, first November 29
Median at 32°F
last January 19, first December 10
Median at 28°F
last January 1, first December 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°FMar 24Mar 9Mar 1Feb 25Feb 21Feb 13Feb 7Jan 31Jan 22
32°FFeb 17Feb 6Jan 31Jan 25Jan 19Jan 13Jan 8Jan 2Dec 25
28°FJan 22Jan 15Jan 9Jan 5Jan 1Dec 30Dec 26Dec 21Dec 12
24°FJan 11Jan 7Jan 4Jan 2Dec 31Dec 28Dec 21Dec 17Dec 13
20°F–––––––––
16°F–––––––––

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°FNov 13Nov 19Nov 23Nov 26Nov 29Dec 1Dec 4Dec 8Dec 13
32°FNov 26Dec 1Dec 4Dec 7Dec 10Dec 15Dec 20Dec 27Jan 7
28°FDec 4Dec 10Dec 14Dec 18Dec 22Dec 26Dec 31Jan 4Jan 10
24°FDec 10Dec 17Dec 20Dec 24Dec 30Jan 1Jan 3Jan 6Jan 9
20°F–––––––––
16°F–––––––––

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°F313303295289283276269261247
32°F358348341335330324317308297
28°F365365365365361356351345336
24°F365365365365365365365365361
20°F365365365365365365365365365
16°F365365365365365365365365365

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
94% of years
28°F or colder
58% of years
24°F or colder
14% of years
20°F or colder
0% of years
16°F or colder
0% 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
2,127
Cooling degree days, base 65°F
1,598
Growing degree days, base 40°F
8,602
Growing degree days, base 45°F
6,819
Growing degree days, base 50°F
5,166
Growing degree days, base 55°F
3,738
Growing degree days, base 60°F
2,550

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January515038
February3420102
March2454229
April13536352
May45129549
June6269713
July0391856
August0378843
September2287735
October45101521
November2784189
December513040

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 9.3 km from Byron. 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 USC00049001 (Tracy Pumping Plt). Public domain.