Lake County climate

Lake County Frost Dates and Growing Season

NOAA 1991-2020 normals for Portageville, 20.5 km from Lake County, elevation 280 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Portageville. 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 March 25 and the first fall freeze around November 7, a growing season of about 227 days.

Median at 36°F
last April 4, first October 27
Median at 32°F
last March 25, first November 7
Median at 28°F
last March 13, first November 20

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°FApr 20Apr 15Apr 11Apr 7Apr 4Apr 2Mar 31Mar 25Mar 19
32°FApr 9Apr 4Apr 1Mar 29Mar 25Mar 21Mar 18Mar 14Mar 7
28°FMar 31Mar 25Mar 20Mar 17Mar 13Mar 9Mar 6Mar 1Feb 23
24°FMar 20Mar 14Mar 10Mar 5Mar 2Feb 28Feb 23Feb 17Feb 9
20°FMar 12Mar 3Feb 28Feb 23Feb 18Feb 12Feb 6Jan 31Jan 25
16°FMar 2Feb 24Feb 16Feb 10Feb 5Jan 31Jan 27Jan 19Jan 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°FOct 14Oct 18Oct 22Oct 24Oct 27Oct 30Nov 1Nov 4Nov 10
32°FOct 24Oct 30Nov 2Nov 5Nov 7Nov 10Nov 15Nov 20Nov 27
28°FNov 4Nov 9Nov 13Nov 16Nov 20Nov 24Nov 28Dec 3Dec 8
24°FNov 13Nov 20Nov 26Nov 30Dec 3Dec 7Dec 11Dec 18Dec 24
20°FNov 27Dec 4Dec 9Dec 14Dec 19Dec 24Dec 29Jan 3Jan 10
16°FDec 6Dec 13Dec 21Dec 27Jan 1Jan 4Jan 10Jan 16Jan 27

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°F228220215210206202198193187
32°F252244238233227223219214207
28°F279271263258252247242236227
24°F306296289282277272266260251
20°F331321314307303296289281272
16°F359343335330323318311306294

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
99% of years
16°F or colder
95% 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
3,960
Cooling degree days, base 65°F
1,680
Growing degree days, base 40°F
7,374
Growing degree days, base 45°F
5,954
Growing degree days, base 50°F
4,677
Growing degree days, base 55°F
3,541
Growing degree days, base 60°F
2,539

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January922011
February714021
March5215103
April22535286
May48163580
June2364811
July0456921
August1398862
September26209633
October19648335
November501496
December805020

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 20.5 km from Lake County. 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 USC00236804 (Portageville). Public domain.