Seward climate

Seward Frost Dates and Growing Season

NOAA 1991-2020 normals for Seward AP, 3.1 km from Seward, elevation 22 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Seward AP. 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 2 and the first fall freeze around October 7, a growing season of about 158 days.

Median at 36°F
last May 20, first September 27
Median at 32°F
last May 2, first October 7
Median at 28°F
last April 15, 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°FJun 2May 29May 26May 23May 20May 17May 15May 11May 5
32°FMay 17May 12May 8May 5May 2Apr 30Apr 28Apr 25Apr 20
28°FApr 29Apr 25Apr 20Apr 17Apr 15Apr 12Apr 9Apr 6Apr 3
24°FApr 18Apr 13Apr 8Apr 6Apr 4Apr 2Mar 31Mar 27Mar 20
20°FApr 9Apr 5Apr 2Mar 31Mar 28Mar 24Mar 20Mar 15Mar 8
16°FApr 3Mar 31Mar 27Mar 22Mar 18Mar 13Mar 9Mar 2Feb 22

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 15Sep 19Sep 22Sep 24Sep 27Sep 29Oct 1Oct 3Oct 8
32°FSep 28Oct 1Oct 2Oct 5Oct 7Oct 10Oct 14Oct 17Oct 23
28°FOct 5Oct 10Oct 14Oct 18Oct 21Oct 24Oct 27Oct 31Nov 6
24°FOct 18Oct 23Oct 27Oct 30Nov 1Nov 5Nov 9Nov 13Nov 19
20°FOct 27Nov 1Nov 4Nov 8Nov 12Nov 16Nov 20Nov 23Dec 1
16°FNov 6Nov 11Nov 17Nov 20Nov 23Nov 27Dec 1Dec 7Dec 17

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°F147141136132129125122117111
32°F175170165161158154150146140
28°F208201195192187184180175168
24°F232224219214210207203197190
20°F255245239235230226220215208
16°F282271263257252247240235227

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
8,960
Cooling degree days, base 65°F
9
Growing degree days, base 40°F
1,976
Growing degree days, base 45°F
1,152
Growing degree days, base 50°F
539
Growing degree days, base 55°F
168
Growing degree days, base 60°F
40

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,20300
February1,01100
March1,05100
April78601
May580024
June381293
July2785193
August2882181
September464045
October76901
November1,00900
December1,14100

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 3.1 km from Seward. 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 USW00026438 (Seward AP). Public domain.