Two Rivers climate

Two Rivers Frost Dates and Growing Season

NOAA 1991-2020 normals for Two Rivers, 4 km from Two Rivers, elevation 605 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Two Rivers. 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 30 and the first fall freeze around September 2, a growing season of about 95 days.

Median at 32°F
last May 30, first September 2
Median at 28°F
last May 16, first September 16

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°F–––––––––
32°FJun 13Jun 5Jun 3Jun 1May 30May 26May 22May 18May 12
28°FMay 31May 28May 24May 19May 16May 12May 9May 4Apr 30
24°FMay 24May 18May 12May 7May 4May 1Apr 28Apr 23Apr 17
20°FMay 14May 7May 2Apr 28Apr 25Apr 22Apr 18Apr 15Apr 10
16°FMay 4Apr 28Apr 24Apr 21Apr 17Apr 14Apr 11Apr 8Apr 4

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°F–––––––––
32°FAug 13Aug 21Aug 25Aug 30Sep 2Sep 4Sep 7Sep 11Sep 17
28°FAug 31Sep 4Sep 8Sep 12Sep 16Sep 19Sep 22Sep 25Sep 30
24°FSep 10Sep 17Sep 21Sep 24Sep 28Sep 30Oct 3Oct 6Oct 11
20°FSep 21Sep 26Sep 29Oct 2Oct 5Oct 7Oct 10Oct 13Oct 18
16°FSep 28Oct 2Oct 6Oct 9Oct 11Oct 13Oct 16Oct 20Oct 23

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°F908378726862575143
32°F1171101051009591857970
28°F14513713212712311711310799
24°F168160154150146142136130121
20°F184177173168164160155150141
16°F194189184180177172168162154

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
12,819
Cooling degree days, base 65°F
54
Growing degree days, base 40°F
2,347
Growing degree days, base 45°F
1,603
Growing degree days, base 50°F
982
Growing degree days, base 55°F
512
Growing degree days, base 60°F
209

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January2,11900
February1,63700
March1,55100
April89106
May484176
June17817294
July12228372
August2908196
September593035
October1,18003
November1,74400
December2,03100

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 km from Two Rivers. 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 USC00509489 (Two Rivers). Public domain.