Norvelt climate

Norvelt Frost Dates and Growing Season

NOAA 1991-2020 normals for Mt Pleasant, 0.9 km from Norvelt, elevation 1003 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mt Pleasant. 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 May 1 and the first fall freeze around October 13, a growing season of about 164 days.

Median at 36°F
last May 13, first October 3
Median at 32°F
last May 1, first October 13
Median at 28°F
last April 20, first October 24

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 29May 24May 20May 17May 13May 9May 6May 2Apr 28
32°FMay 19May 13May 8May 5May 1Apr 29Apr 26Apr 22Apr 17
28°FMay 8May 1Apr 27Apr 24Apr 20Apr 17Apr 14Apr 11Apr 6
24°FApr 23Apr 18Apr 14Apr 10Apr 8Apr 5Apr 1Mar 29Mar 23
20°FApr 11Apr 7Apr 3Mar 31Mar 29Mar 25Mar 20Mar 16Mar 10
16°FApr 1Mar 27Mar 23Mar 19Mar 16Mar 12Mar 8Mar 3Feb 25

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°FSep 21Sep 25Sep 28Oct 1Oct 3Oct 5Oct 7Oct 10Oct 14
32°FOct 3Oct 6Oct 8Oct 11Oct 13Oct 15Oct 19Oct 22Oct 26
28°FOct 10Oct 15Oct 19Oct 22Oct 24Oct 27Oct 30Nov 2Nov 8
24°FOct 23Oct 28Nov 1Nov 2Nov 5Nov 8Nov 12Nov 16Nov 23
20°FNov 2Nov 6Nov 10Nov 13Nov 16Nov 20Nov 26Dec 1Dec 7
16°FNov 8Nov 14Nov 20Nov 25Nov 30Dec 4Dec 8Dec 15Dec 24

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°F163157151147143138134129121
32°F184177172168164160156152145
28°F207200194189186182178173165
24°F237228221216212207203197190
20°F260251244239234229224218212
16°F289279271265259253246240231

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
5,855
Cooling degree days, base 65°F
587
Growing degree days, base 40°F
5,054
Growing degree days, base 45°F
3,860
Growing degree days, base 50°F
2,814
Growing degree days, base 55°F
1,917
Growing degree days, base 60°F
1,165

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,11404
February95805
March811029
April4786112
May21433299
June49118519
July8197654
August15167617
September11859395
October4147140
November705032
December971010

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 0.9 km from Norvelt. 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 USC00366042 (Mt Pleasant). Public domain.