Frontenac climate

Frontenac Frost Dates and Growing Season

NOAA 1991-2020 normals for Pittsburg, 7.4 km from Frontenac, elevation 908 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pittsburg. 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 7 and the first fall freeze around October 30, a growing season of about 203 days.

Median at 36°F
last April 18, first October 21
Median at 32°F
last April 7, first October 30
Median at 28°F
last March 29, first November 6

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 2Apr 29Apr 25Apr 22Apr 18Apr 15Apr 12Apr 8Apr 3
32°FApr 24Apr 18Apr 14Apr 10Apr 7Apr 5Apr 1Mar 30Mar 24
28°FApr 12Apr 7Apr 4Apr 1Mar 29Mar 26Mar 22Mar 18Mar 12
24°FApr 2Mar 29Mar 24Mar 20Mar 17Mar 14Mar 11Mar 6Mar 1
20°FMar 24Mar 18Mar 14Mar 10Mar 6Mar 3Feb 28Feb 24Feb 17
16°FMar 17Mar 11Mar 6Mar 2Feb 26Feb 22Feb 18Feb 11Feb 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°FOct 5Oct 12Oct 16Oct 19Oct 21Oct 24Oct 26Oct 29Nov 2
32°FOct 17Oct 22Oct 25Oct 28Oct 30Nov 1Nov 3Nov 6Nov 10
28°FOct 25Oct 30Nov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 21
24°FNov 1Nov 5Nov 9Nov 12Nov 15Nov 18Nov 22Nov 26Dec 1
20°FNov 7Nov 12Nov 16Nov 21Nov 24Nov 29Dec 1Dec 6Dec 12
16°FNov 16Nov 24Nov 29Dec 2Dec 6Dec 11Dec 16Dec 22Dec 31

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°F203196192188184180177172165
32°F224217212208203199196191183
28°F244236230226222218213209202
24°F266258252247243237232226218
20°F288279273267262256251245237
16°F312302295289283277272265256

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
4,337
Cooling degree days, base 65°F
1,622
Growing degree days, base 40°F
7,099
Growing degree days, base 45°F
5,717
Growing degree days, base 50°F
4,480
Growing degree days, base 55°F
3,386
Growing degree days, base 60°F
2,437

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January98405
February749022
March5448101
April26525251
May92123500
June3313760
July0469934
August0429894
September28206629
October23544304
November562470
December876010

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 7.4 km from Frontenac. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00146414 (Pittsburg). Public domain.