Niles climate

Niles Frost Dates and Growing Season

NOAA 1991-2020 normals for Niles, 1.5 km from Niles, elevation 650 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Niles. 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 27 and the first fall freeze around October 25, a growing season of about 180 days.

Median at 36°F
last May 8, first October 11
Median at 32°F
last April 27, first October 25
Median at 28°F
last April 13, first November 6

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

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°F178170164160156151145140134
32°F202194189184180176171165156
28°F228221216212208204198192184
24°F256248242237233229224218210
20°F278271264259253249244238231
16°F298289283278274269265258249

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
6,053
Cooling degree days, base 65°F
719
Growing degree days, base 40°F
5,166
Growing degree days, base 45°F
4,006
Growing degree days, base 50°F
2,985
Growing degree days, base 55°F
2,099
Growing degree days, base 60°F
1,340

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,21500
February1,02301
March842228
April479397
May20140321
June26150574
July7235693
August13198649
September10183433
October38310158
November714027
December1,04902

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 1.5 km from Niles. 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 USC00205892 (Niles). Public domain.