Howells climate

Howells Frost Dates and Growing Season

NOAA 1991-2020 normals for Howells, 0.8 km from Howells, elevation 1520 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Howells. 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 25 and the first fall freeze around October 11, a growing season of about 168 days.

Median at 36°F
last May 4, first October 1
Median at 32°F
last April 25, first October 11
Median at 28°F
last April 16, first October 21

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 17May 12May 9May 6May 4May 2Apr 30Apr 27Apr 21
32°FMay 8May 3May 1Apr 28Apr 25Apr 23Apr 20Apr 17Apr 13
28°FApr 30Apr 26Apr 22Apr 19Apr 16Apr 13Apr 10Apr 7Apr 3
24°FApr 21Apr 17Apr 14Apr 10Apr 8Apr 5Apr 2Mar 30Mar 22
20°FApr 14Apr 8Apr 4Apr 1Mar 30Mar 27Mar 22Mar 17Mar 11
16°FApr 4Mar 31Mar 27Mar 22Mar 19Mar 15Mar 11Mar 7Mar 2

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 16Sep 22Sep 26Sep 29Oct 1Oct 4Oct 6Oct 10Oct 14
32°FSep 25Oct 1Oct 5Oct 8Oct 11Oct 15Oct 17Oct 21Oct 25
28°FOct 3Oct 10Oct 15Oct 19Oct 21Oct 23Oct 26Oct 29Nov 2
24°FOct 16Oct 21Oct 24Oct 28Oct 30Nov 1Nov 4Nov 8Nov 13
20°FOct 24Oct 30Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 25
16°FNov 1Nov 6Nov 10Nov 14Nov 16Nov 19Nov 23Nov 27Dec 3

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°F166160156152149145142137130
32°F185180176172168164159155148
28°F206198194189186182178174167
24°F225218213209204200196191183
20°F244237231227222218213207200
16°F265257250246242236231225217

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
6,319
Cooling degree days, base 65°F
1,004
Growing degree days, base 40°F
5,507
Growing degree days, base 45°F
4,359
Growing degree days, base 50°F
3,335
Growing degree days, base 55°F
2,429
Growing degree days, base 60°F
1,652

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,29100
February1,06202
March815136
April4637118
May18068367
June23230657
July5328789
August9248704
September97107464
October40115174
November798024
December1,17601

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 0.8 km from Howells. 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 USC00254035 (Howells). Public domain.