Manhattan climate

Manhattan Frost Dates and Growing Season

NOAA 1991-2020 normals for Logan Landfill, 6.4 km from Manhattan, elevation 4243 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Logan Landfill. 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 26 and the first fall freeze around September 15, a growing season of about 111 days.

Median at 36°F
last June 12, first September 3
Median at 32°F
last May 26, first September 15
Median at 28°F
last May 11, first September 27

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°FJul 3Jun 24Jun 19Jun 16Jun 12Jun 9Jun 5Jun 2May 29
32°FJun 12Jun 4Jun 1May 29May 26May 23May 19May 16May 11
28°FMay 27May 21May 17May 13May 11May 8May 5May 3Apr 29
24°FMay 15May 9May 5May 2Apr 30Apr 28Apr 24Apr 20Apr 14
20°FMay 3Apr 29Apr 24Apr 21Apr 17Apr 13Apr 10Apr 6Apr 2
16°FApr 24Apr 17Apr 12Apr 7Apr 4Apr 1Mar 29Mar 23Mar 15

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°FAug 17Aug 24Aug 29Sep 1Sep 3Sep 6Sep 9Sep 12Sep 16
32°FSep 1Sep 6Sep 9Sep 12Sep 15Sep 17Sep 21Sep 24Sep 28
28°FSep 12Sep 18Sep 22Sep 25Sep 27Sep 29Oct 1Oct 4Oct 8
24°FSep 23Sep 28Oct 1Oct 3Oct 5Oct 8Oct 11Oct 14Oct 18
20°FOct 1Oct 5Oct 9Oct 13Oct 16Oct 20Oct 23Oct 26Oct 30
16°FOct 9Oct 15Oct 20Oct 23Oct 26Oct 29Nov 1Nov 4Nov 9

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°F1029691858176716456
32°F1321241201151111071029790
28°F155149145142138133128124117
24°F177171167162159155151146139
20°F204196190186181177172167159
16°F226219214208203199194188178

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
8,291
Cooling degree days, base 65°F
196
Growing degree days, base 40°F
3,323
Growing degree days, base 45°F
2,383
Growing degree days, base 50°F
1,612
Growing degree days, base 55°F
992
Growing degree days, base 60°F
519

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,36200
February1,11801
March97801
April698015
May459198
June21517266
July46102521
August7566458
September28411211
October679138
November1,03701
December1,33900

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 6.4 km from Manhattan. 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 USC00245123 (Logan Landfill). Public domain.