Pennington climate

Pennington Frost Dates and Growing Season

NOAA 1991-2020 normals for Trenton Mercer CO AP, 6.1 km from Pennington, elevation 184 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Trenton Mercer CO AP. 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 10 and the first fall freeze around November 1, a growing season of about 202 days.

Median at 36°F
last April 25, first October 20
Median at 32°F
last April 10, first November 1
Median at 28°F
last March 31, first November 12

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 11May 6May 1Apr 28Apr 25Apr 22Apr 19Apr 15Apr 10
32°FApr 25Apr 20Apr 16Apr 13Apr 10Apr 8Apr 5Apr 3Mar 30
28°FApr 12Apr 7Apr 4Apr 2Mar 31Mar 28Mar 25Mar 21Mar 16
24°FApr 1Mar 28Mar 24Mar 21Mar 18Mar 14Mar 10Mar 6Feb 28
20°FMar 23Mar 18Mar 14Mar 10Mar 7Mar 4Feb 28Feb 24Feb 15
16°FMar 13Mar 8Mar 3Feb 28Feb 24Feb 18Feb 12Feb 7Jan 31

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 6Oct 10Oct 14Oct 17Oct 20Oct 23Oct 26Oct 30Nov 2
32°FOct 15Oct 21Oct 25Oct 29Nov 1Nov 3Nov 5Nov 8Nov 13
28°FOct 29Nov 2Nov 5Nov 8Nov 12Nov 14Nov 18Nov 22Nov 29
24°FNov 9Nov 13Nov 16Nov 20Nov 24Nov 28Dec 1Dec 5Dec 11
20°FNov 17Nov 25Nov 30Dec 3Dec 7Dec 11Dec 16Dec 22Dec 30
16°FDec 2Dec 9Dec 15Dec 21Dec 25Dec 31Jan 4Jan 9Jan 16

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°F197191186181176173168163156
32°F223215210205202199194188180
28°F250241236230226222218213205
24°F274266260256251246242236229
20°F302293287281277271266260253
16°F328321314308303299293286277

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
4,977
Cooling degree days, base 65°F
1,050
Growing degree days, base 40°F
5,979
Growing degree days, base 45°F
4,687
Growing degree days, base 50°F
3,551
Growing degree days, base 55°F
2,569
Growing degree days, base 60°F
1,734

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,02303
February85806
March722133
April38712144
May14855375
June20199628
July0351815
August2294756
September51123522
October30416210
November588046
December873012

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 6.1 km from Pennington. 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 USW00014792 (Trenton Mercer CO AP). Public domain.