Leavenworth climate

Leavenworth Frost Dates and Growing Season

NOAA 1991-2020 normals for Leavenworth 3 S, 4.3 km from Leavenworth, elevation 1128 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Leavenworth 3 S. 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 10 and the first fall freeze around September 30, a growing season of about 142 days.

Median at 36°F
last May 31, first September 18
Median at 32°F
last May 10, first September 30
Median at 28°F
last April 25, first October 13

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

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 4Sep 9Sep 12Sep 15Sep 18Sep 21Sep 23Sep 25Sep 29
32°FSep 18Sep 23Sep 26Sep 28Sep 30Oct 2Oct 5Oct 8Oct 14
28°FOct 1Oct 4Oct 7Oct 10Oct 13Oct 16Oct 19Oct 23Oct 29
24°FOct 11Oct 18Oct 22Oct 25Oct 28Oct 30Nov 3Nov 8Nov 15
20°FOct 25Oct 31Nov 3Nov 7Nov 11Nov 15Nov 18Nov 22Nov 28
16°FNov 5Nov 12Nov 18Nov 22Nov 25Nov 29Dec 2Dec 7Dec 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°F1311241191141091051009486
32°F162156151146142138133129123
28°F194185179176171168163158151
24°F235225219215209205200193183
20°F270261255249245240235229222
16°F300290283277272267261254245

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
6,806
Cooling degree days, base 65°F
381
Growing degree days, base 40°F
4,045
Growing degree days, base 45°F
2,985
Growing degree days, base 50°F
2,094
Growing degree days, base 55°F
1,357
Growing degree days, base 60°F
784

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,19500
February93100
March80102
April551036
May30910191
June14641346
July35159589
August33145577
September18327299
October540053
November89900
December1,18400

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 4.3 km from Leavenworth. 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 USC00454572 (Leavenworth 3 S). Public domain.