Vernon climate

Vernon Frost Dates and Growing Season

NOAA 1991-2020 normals for Durand Wwtp, 3.5 km from Vernon, elevation 770 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Durand 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 May 3 and the first fall freeze around October 11, a growing season of about 159 days.

Median at 36°F
last May 13, first September 30
Median at 32°F
last May 3, first October 11
Median at 28°F
last April 22, 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 27May 23May 19May 17May 13May 10May 7May 3Apr 29
32°FMay 19May 14May 9May 6May 3Apr 30Apr 27Apr 25Apr 21
28°FMay 8May 1Apr 29Apr 25Apr 22Apr 19Apr 17Apr 14Apr 10
24°FApr 25Apr 20Apr 17Apr 14Apr 11Apr 8Apr 5Apr 3Mar 31
20°FApr 14Apr 8Apr 5Apr 3Apr 1Mar 30Mar 26Mar 21Mar 17
16°FApr 4Apr 1Mar 29Mar 25Mar 22Mar 19Mar 16Mar 13Mar 8

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 18Sep 22Sep 25Sep 27Sep 30Oct 1Oct 4Oct 6Oct 11
32°FSep 29Oct 2Oct 5Oct 8Oct 11Oct 14Oct 17Oct 20Oct 25
28°FOct 9Oct 15Oct 18Oct 21Oct 24Oct 27Oct 30Nov 1Nov 6
24°FOct 21Oct 27Oct 31Nov 2Nov 5Nov 7Nov 10Nov 14Nov 19
20°FNov 1Nov 5Nov 9Nov 13Nov 17Nov 21Nov 25Nov 30Dec 4
16°FNov 10Nov 16Nov 21Nov 25Nov 29Dec 1Dec 4Dec 9Dec 16

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°F158151146142138134130126120
32°F179172168163159155151146139
28°F203197192188184179174170162
24°F229221216211207204200195188
20°F253245240235231227222217211
16°F274266261256251246242236230

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
6,888
Cooling degree days, base 65°F
635
Growing degree days, base 40°F
4,670
Growing degree days, base 45°F
3,598
Growing degree days, base 50°F
2,661
Growing degree days, base 55°F
1,851
Growing degree days, base 60°F
1,170

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,30300
February1,14101
March973114
April585158
May25935271
June52137536
July11226680
August21168612
September14760368
October4696107
November798014
December1,13001

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 3.5 km from Vernon. 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 USC00202328 (Durand Wwtp). Public domain.