Trafalgar climate

Trafalgar Frost Dates and Growing Season

NOAA 1991-2020 normals for Franklin Wwtp, 11.1 km from Trafalgar, elevation 720 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Franklin Wwtp. 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 20 and the first fall freeze around October 19, a growing season of about 180 days.

Median at 36°F
last May 1, first October 10
Median at 32°F
last April 20, first October 19
Median at 28°F
last April 8, first October 29

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 16May 11May 7May 4May 1Apr 29Apr 25Apr 22Apr 18
32°FMay 7May 1Apr 27Apr 23Apr 20Apr 18Apr 15Apr 11Apr 7
28°FApr 24Apr 19Apr 15Apr 12Apr 8Apr 5Apr 3Mar 31Mar 25
24°FApr 12Apr 7Apr 3Apr 1Mar 30Mar 26Mar 23Mar 19Mar 13
20°FApr 1Mar 29Mar 24Mar 21Mar 18Mar 15Mar 12Mar 8Mar 3
16°FMar 24Mar 19Mar 16Mar 12Mar 10Mar 6Mar 3Feb 28Feb 20

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 29Oct 3Oct 5Oct 8Oct 10Oct 12Oct 14Oct 17Oct 23
32°FOct 7Oct 11Oct 15Oct 17Oct 19Oct 22Oct 24Oct 27Nov 1
28°FOct 17Oct 21Oct 24Oct 26Oct 29Oct 31Nov 2Nov 6Nov 12
24°FOct 26Oct 31Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 25
20°FNov 4Nov 8Nov 13Nov 16Nov 20Nov 24Nov 29Dec 3Dec 9
16°FNov 12Nov 18Nov 24Nov 29Dec 2Dec 5Dec 10Dec 16Dec 23

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°F179172168164160157153148142
32°F199193187183180176171167160
28°F221214210205201198193188181
24°F248239234229225220215211205
20°F272264258252247243239233225
16°F295284278273268264259252243

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
5,752
Cooling degree days, base 65°F
897
Growing degree days, base 40°F
5,563
Growing degree days, base 45°F
4,367
Growing degree days, base 50°F
3,303
Growing degree days, base 55°F
2,368
Growing degree days, base 60°F
1,564

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,18902
February98604
March779138
April4236134
May16766376
June20201631
July2281744
August7226684
September72103483
October37113174
November707029
December1,03105

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 11.1 km from Trafalgar. 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 USC00123091 (Franklin Wwtp). Public domain.