Trafford climate

Trafford Frost Dates and Growing Season

NOAA 1991-2020 normals for Murrysville 2 Sw, 4.1 km from Trafford, elevation 860 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Murrysville 2 Sw. 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 22 and the first fall freeze around October 25, a growing season of about 186 days.

Median at 36°F
last May 5, first October 13
Median at 32°F
last April 22, first October 25
Median at 28°F
last April 7, first November 5

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 20May 16May 12May 8May 5May 1Apr 28Apr 23Apr 19
32°FMay 12May 5Apr 29Apr 25Apr 22Apr 20Apr 17Apr 12Apr 7
28°FApr 23Apr 18Apr 15Apr 11Apr 7Apr 5Apr 2Mar 31Mar 24
24°FApr 10Apr 5Apr 2Mar 31Mar 28Mar 25Mar 21Mar 18Mar 13
20°FMar 31Mar 27Mar 23Mar 19Mar 17Mar 14Mar 11Mar 6Feb 28
16°FMar 23Mar 18Mar 15Mar 11Mar 8Mar 4Feb 28Feb 23Feb 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 1Oct 5Oct 8Oct 10Oct 13Oct 16Oct 19Oct 22Oct 26
32°FOct 10Oct 15Oct 19Oct 22Oct 25Oct 28Oct 30Nov 2Nov 6
28°FOct 23Oct 28Oct 31Nov 2Nov 5Nov 8Nov 11Nov 15Nov 20
24°FNov 3Nov 7Nov 11Nov 14Nov 17Nov 20Nov 24Nov 28Dec 3
20°FNov 11Nov 16Nov 21Nov 25Nov 28Dec 1Dec 6Dec 11Dec 20
16°FNov 21Nov 28Dec 2Dec 7Dec 12Dec 17Dec 23Dec 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°F181174169165161157152147140
32°F207199194190186181176170163
28°F234226220216213208203198191
24°F258250244239235231226221214
20°F283275267262257252247241233
16°F306298292287281275270264255

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
5,490
Cooling degree days, base 65°F
945
Growing degree days, base 40°F
5,634
Growing degree days, base 45°F
4,412
Growing degree days, base 50°F
3,342
Growing degree days, base 55°F
2,411
Growing degree days, base 60°F
1,611

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,09701
February94504
March789020
April4154133
May14566395
June12191630
July4309770
August4258719
September85103469
October35713173
November676025
December96103

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 4.1 km from Trafford. 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 USC00366111 (Murrysville 2 Sw). Public domain.