Frederick climate

Frederick Frost Dates and Growing Season

NOAA 1991-2020 normals for Tipton 4S Mesonet, 12.2 km from Frederick, elevation 1269 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tipton 4S Mesonet. 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 3 and the first fall freeze around November 6, a growing season of about 217 days.

Median at 36°F
last April 15, first October 29
Median at 32°F
last April 3, first November 6
Median at 28°F
last March 19, first November 14

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 1Apr 26Apr 21Apr 18Apr 15Apr 11Apr 7Apr 3Mar 27
32°FApr 21Apr 16Apr 11Apr 6Apr 3Mar 30Mar 25Mar 20Mar 12
28°FApr 9Apr 3Mar 30Mar 23Mar 19Mar 14Mar 9Mar 5Feb 27
24°FMar 27Mar 17Mar 12Mar 8Mar 4Feb 28Feb 24Feb 18Feb 8
20°FMar 12Mar 5Mar 1Feb 24Feb 18Feb 10Feb 3Jan 29Jan 17
16°FMar 3Feb 24Feb 15Feb 7Feb 2Jan 28Jan 21Jan 11Dec 26

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 16Oct 20Oct 23Oct 26Oct 29Nov 1Nov 3Nov 6Nov 10
32°FOct 22Oct 27Nov 1Nov 3Nov 6Nov 9Nov 11Nov 15Nov 21
28°FOct 28Nov 3Nov 7Nov 11Nov 14Nov 18Nov 22Nov 26Dec 3
24°FNov 6Nov 13Nov 18Nov 23Nov 27Dec 1Dec 4Dec 11Dec 18
20°FNov 18Nov 26Nov 30Dec 4Dec 9Dec 15Dec 21Dec 30Jan 10
16°FNov 26Dec 2Dec 9Dec 16Dec 24Dec 31Jan 9Jan 20Feb 2

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°F219212206201197193188183175
32°F242234227222217212206201193
28°F267257252246240234229223214
24°F296285278272266260254246234
20°F334322313305298290282275263
16°F365355344335328321310303290

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
99% of years
16°F or colder
84% 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
3,263
Cooling degree days, base 65°F
2,377
Growing degree days, base 40°F
8,522
Growing degree days, base 45°F
6,990
Growing degree days, base 50°F
5,610
Growing degree days, base 55°F
4,386
Growing degree days, base 60°F
3,312

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January762017
February577255
March38413173
April18150336
May37238667
June0475925
July06091,074
August05691,033
September10322762
October14493427
November4435118
December724024

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 Frederick. 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 USC00348879 (Tipton 4S Mesonet). Public domain.