Moscow climate

Moscow Frost Dates and Growing Season

NOAA 1991-2020 normals for Long Falls Dam, 29.4 km from Moscow, elevation 1160 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Long Falls Dam. 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 13 and the first fall freeze around September 30, a growing season of about 138 days.

Median at 36°F
last May 27, first September 18
Median at 32°F
last May 13, first September 30
Median at 28°F
last May 1, first October 12

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 8Jun 4Jun 2May 31May 27May 24May 21May 18May 13
32°FMay 27May 22May 19May 16May 13May 10May 8May 4Apr 30
28°FMay 14May 9May 6May 3May 1Apr 30Apr 27Apr 25Apr 21
24°FMay 2Apr 29Apr 26Apr 23Apr 21Apr 18Apr 15Apr 12Apr 8
20°FApr 23Apr 19Apr 16Apr 13Apr 10Apr 8Apr 6Apr 4Apr 1
16°FApr 15Apr 11Apr 7Apr 6Apr 4Apr 3Apr 1Mar 30Mar 24

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 5Sep 9Sep 12Sep 15Sep 18Sep 21Sep 24Sep 28Oct 3
32°FSep 15Sep 20Sep 24Sep 27Sep 30Oct 2Oct 5Oct 8Oct 13
28°FSep 29Oct 2Oct 5Oct 9Oct 12Oct 17Oct 21Oct 26Oct 30
24°FOct 11Oct 17Oct 22Oct 26Oct 29Nov 1Nov 3Nov 6Nov 11
20°FOct 30Nov 1Nov 4Nov 7Nov 10Nov 12Nov 15Nov 18Nov 22
16°FNov 6Nov 11Nov 14Nov 16Nov 19Nov 21Nov 23Nov 27Dec 1

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°F13312512111711311010510196
32°F156150145142138134131126119
28°F184177172167163159156151145
24°F208201197193189184180174168
20°F227221217214210207203198193
16°F243238234230227224220217211

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
9,011
Cooling degree days, base 65°F
194
Growing degree days, base 40°F
3,309
Growing degree days, base 45°F
2,416
Growing degree days, base 50°F
1,643
Growing degree days, base 55°F
998
Growing degree days, base 60°F
506

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,58900
February1,38500
March1,26001
April82409
May4384112
June16634323
July5582493
August8157440
September26317224
October635139
November96602
December1,35200

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 29.4 km from Moscow. 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 USC00174781 (Long Falls Dam). Public domain.