Poplar climate

Poplar Frost Dates and Growing Season

NOAA 1991-2020 normals for Wolf Point 29 Ene, 22.9 km from Poplar, elevation 2085 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wolf Point 29 Ene. 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 24 and the first fall freeze around September 14, a growing season of about 110 days.

Median at 36°F
last June 3, first September 4
Median at 32°F
last May 24, first September 14
Median at 28°F
last May 14, first September 22

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 16Jun 11Jun 6Jun 3May 31May 29May 26May 21
32°FJun 6Jun 1May 29May 26May 24May 21May 19May 16May 12
28°FMay 26May 22May 19May 16May 14May 11May 8May 5May 1
24°FMay 15May 12May 9May 5May 3Apr 30Apr 28Apr 24Apr 19
20°FMay 8May 3Apr 30Apr 27Apr 23Apr 20Apr 16Apr 12Apr 7
16°FApr 28Apr 22Apr 19Apr 15Apr 12Apr 8Apr 5Apr 2Mar 27

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 21Aug 26Aug 30Sep 1Sep 4Sep 7Sep 9Sep 12Sep 16
32°FSep 1Sep 5Sep 8Sep 11Sep 14Sep 15Sep 18Sep 22Sep 25
28°FSep 8Sep 13Sep 16Sep 20Sep 22Sep 24Sep 26Sep 30Oct 4
24°FSep 15Sep 21Sep 24Sep 26Sep 29Oct 2Oct 5Oct 8Oct 13
20°FSep 22Sep 28Oct 2Oct 6Oct 9Oct 12Oct 16Oct 19Oct 24
16°FOct 2Oct 8Oct 13Oct 16Oct 19Oct 22Oct 24Oct 27Nov 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°F10810399949085817565
32°F1271221181141101061039892
28°F147141137133130127122117111
24°F168161156151147144140136129
20°F190181176171167163159153146
16°F211203198193189185179174167

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
9,210
Cooling degree days, base 65°F
331
Growing degree days, base 40°F
3,599
Growing degree days, base 45°F
2,683
Growing degree days, base 50°F
1,888
Growing degree days, base 55°F
1,221
Growing degree days, base 60°F
695

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,65400
February1,36800
March1,13902
April702024
May3987144
June13735351
July36136566
August59130537
September28322227
October725137
November1,15501
December1,55500

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 22.9 km from Poplar. 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 USW00094060 (Wolf Point 29 Ene). Public domain.