Bear River climate

Bear River Frost Dates and Growing Season

NOAA 1991-2020 normals for Evanston Burns Fld, 12.3 km from Bear River, elevation 7163 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Evanston Burns Fld. 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 June 3 and the first fall freeze around September 25, a growing season of about 113 days.

Median at 36°F
last June 13, first September 16
Median at 32°F
last June 3, first September 25
Median at 28°F
last May 17, first October 4

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 24Jun 21Jun 18Jun 15Jun 13Jun 11Jun 8Jun 5May 31
32°FJun 17Jun 13Jun 9Jun 6Jun 3May 31May 27May 21May 16
28°FJun 6Jun 1May 25May 21May 17May 13May 9May 5Apr 29
24°FMay 20May 13May 8May 4May 2Apr 29Apr 26Apr 22Apr 17
20°FMay 9May 1Apr 27Apr 23Apr 20Apr 16Apr 12Apr 8Apr 2
16°FApr 24Apr 18Apr 13Apr 9Apr 5Apr 2Mar 31Mar 24Mar 16

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 1Sep 6Sep 10Sep 14Sep 16Sep 18Sep 20Sep 23Sep 26
32°FSep 11Sep 17Sep 20Sep 22Sep 25Sep 27Sep 30Oct 3Oct 8
28°FSep 19Sep 26Sep 29Oct 1Oct 4Oct 8Oct 12Oct 15Oct 21
24°FOct 1Oct 5Oct 9Oct 13Oct 17Oct 20Oct 23Oct 27Oct 31
20°FOct 10Oct 16Oct 20Oct 24Oct 27Oct 31Nov 2Nov 5Nov 10
16°FOct 20Oct 26Oct 31Nov 2Nov 5Nov 8Nov 11Nov 14Nov 19

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°F110105100959289858275
32°F13512812211811310910510092
28°F161154148143138133128123113
24°F188181175170165161156149137
20°F213205198193189184179173164
16°F238229223218213208202195187

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
8,428
Cooling degree days, base 65°F
204
Growing degree days, base 40°F
3,312
Growing degree days, base 45°F
2,415
Growing degree days, base 50°F
1,663
Growing degree days, base 55°F
1,043
Growing degree days, base 60°F
549

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,34200
February1,17200
March1,04301
April77709
May506188
June22417268
July30106541
August5473485
September2688231
October654039
November1,01701
December1,34100

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 12.3 km from Bear River. 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 USW00004111 (Evanston Burns Fld). Public domain.