Reading climate

Reading Frost Dates and Growing Season

NOAA 1991-2020 normals for Reading Spaatz Fld, 4.8 km from Reading, elevation 341 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Reading Spaatz Fld. 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 14 and the first fall freeze around October 29, a growing season of about 197 days.

Median at 36°F
last April 28, first October 17
Median at 32°F
last April 14, first October 29
Median at 28°F
last April 1, first November 8

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 13May 7May 3Apr 30Apr 28Apr 24Apr 22Apr 18Apr 14
32°FApr 30Apr 24Apr 21Apr 18Apr 14Apr 11Apr 8Apr 5Apr 1
28°FApr 15Apr 10Apr 6Apr 3Apr 1Mar 30Mar 27Mar 22Mar 17
24°FApr 3Mar 31Mar 28Mar 24Mar 21Mar 18Mar 14Mar 10Mar 5
20°FMar 24Mar 19Mar 16Mar 13Mar 10Mar 6Mar 3Feb 28Feb 22
16°FMar 15Mar 9Mar 6Mar 3Feb 28Feb 25Feb 20Feb 14Feb 6

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 4Oct 8Oct 11Oct 14Oct 17Oct 20Oct 23Oct 27Nov 1
32°FOct 13Oct 19Oct 22Oct 26Oct 29Nov 1Nov 2Nov 6Nov 10
28°FOct 25Oct 31Nov 2Nov 5Nov 8Nov 12Nov 15Nov 19Nov 24
24°FNov 5Nov 11Nov 14Nov 18Nov 21Nov 25Nov 29Dec 3Dec 8
20°FNov 16Nov 24Nov 29Dec 2Dec 5Dec 10Dec 14Dec 20Dec 26
16°FDec 1Dec 7Dec 12Dec 18Dec 21Dec 25Dec 31Jan 5Jan 13

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°F193186181176172168163159152
32°F217211207202197193188182173
28°F243235230225221217212208201
24°F268261254249244240236231223
20°F295287282276272267262257248
16°F320311306300296291287280270

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
5,127
Cooling degree days, base 65°F
1,056
Growing degree days, base 40°F
5,918
Growing degree days, base 45°F
4,652
Growing degree days, base 50°F
3,538
Growing degree days, base 55°F
2,568
Growing degree days, base 60°F
1,740

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,06002
February89204
March731031
April38511147
May14264391
June17215648
July0346811
August3289752
September60115506
October31915200
November612040
December90807

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 4.8 km from Reading. 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 USW00014712 (Reading Spaatz Fld). Public domain.