Prospect climate

Prospect Frost Dates and Growing Season

NOAA 1991-2020 normals for Mt Carmel, 12.2 km from Prospect, elevation 180 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mt Carmel. 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 18 and the first fall freeze around October 26, a growing season of about 191 days.

Median at 36°F
last May 1, first October 15
Median at 32°F
last April 18, first October 26
Median at 28°F
last April 5, 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 16May 10May 6May 3May 1Apr 28Apr 25Apr 22Apr 18
32°FMay 3Apr 28Apr 23Apr 20Apr 18Apr 15Apr 12Apr 9Apr 5
28°FApr 19Apr 13Apr 10Apr 7Apr 5Apr 2Mar 31Mar 29Mar 23
24°FApr 6Apr 2Mar 31Mar 29Mar 26Mar 23Mar 19Mar 16Mar 11
20°FMar 30Mar 27Mar 23Mar 19Mar 16Mar 14Mar 10Mar 7Mar 2
16°FMar 23Mar 17Mar 13Mar 10Mar 7Mar 3Feb 28Feb 22Feb 14

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 2Oct 6Oct 9Oct 12Oct 15Oct 18Oct 21Oct 25Oct 30
32°FOct 11Oct 16Oct 20Oct 23Oct 26Oct 29Nov 1Nov 4Nov 9
28°FOct 22Oct 27Oct 31Nov 3Nov 6Nov 9Nov 12Nov 16Nov 22
24°FNov 2Nov 7Nov 12Nov 15Nov 19Nov 23Nov 27Dec 1Dec 6
20°FNov 16Nov 22Nov 26Nov 30Dec 2Dec 5Dec 9Dec 14Dec 21
16°FNov 30Dec 4Dec 7Dec 11Dec 16Dec 20Dec 24Dec 29Jan 4

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°F186178174170166162158154148
32°F208203199195191187183178172
28°F235227221218214210206201195
24°F261252246242238234230224217
20°F284277271266261257253247240
16°F309300293289284278274268261

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
5,642
Cooling degree days, base 65°F
818
Growing degree days, base 40°F
5,337
Growing degree days, base 45°F
4,131
Growing degree days, base 50°F
3,078
Growing degree days, base 55°F
2,181
Growing degree days, base 60°F
1,430

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11701
February94401
March82909
April474382
May20332299
June33140557
July1287752
August4245707
September81102472
October3538167
November656028
December94904

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 12.2 km from Prospect. 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 USC00065077 (Mt Carmel). Public domain.