Pittsburg climate

Pittsburg Frost Dates and Growing Season

NOAA 1991-2020 normals for First Connecticut Lake, 9 km from Pittsburg, elevation 1650 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for First Connecticut Lake. 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 25 and the first fall freeze around September 24, a growing season of about 121 days.

Median at 36°F
last June 7, first September 11
Median at 32°F
last May 25, first September 24
Median at 28°F
last May 9, first October 5

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 28Jun 19Jun 14Jun 10Jun 7Jun 4Jun 2May 30May 25
32°FJun 8Jun 4May 31May 28May 25May 21May 18May 14May 9
28°FMay 27May 22May 17May 13May 9May 6May 2Apr 30Apr 25
24°FMay 12May 5May 1Apr 29Apr 27Apr 24Apr 22Apr 19Apr 15
20°FApr 27Apr 24Apr 22Apr 19Apr 17Apr 15Apr 13Apr 10Apr 7
16°FApr 23Apr 19Apr 16Apr 14Apr 11Apr 9Apr 7Apr 4Apr 2

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

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°F114108103979389847867
32°F14213412912512111711210798
28°F169162157152148143138133126
24°F193187180177173168163158152
20°F213207203199196192188183177
16°F227222218214211208204200194

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
9,567
Cooling degree days, base 65°F
143
Growing degree days, base 40°F
3,087
Growing degree days, base 45°F
2,216
Growing degree days, base 50°F
1,470
Growing degree days, base 55°F
860
Growing degree days, base 60°F
413

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,67200
February1,46200
March1,33601
April86109
May4724105
June19526289
July8459440
August11441393
September30812192
October668038
November99604
December1,39800

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 km from Pittsburg. 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 USC00272999 (First Connecticut Lake). Public domain.