Proctor climate

Proctor Frost Dates and Growing Season

NOAA 1991-2020 normals for Duluth, 10.1 km from Proctor, elevation 1428 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Duluth. 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 October 1, a growing season of about 140 days.

Median at 36°F
last May 26, first September 23
Median at 32°F
last May 13, first October 1
Median at 28°F
last April 30, first October 13

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 9Jun 4Jun 1May 30May 26May 24May 20May 16May 11
32°FMay 29May 23May 19May 16May 13May 9May 6May 3Apr 29
28°FMay 16May 9May 5May 2Apr 30Apr 28Apr 25Apr 21Apr 17
24°FMay 2Apr 29Apr 25Apr 22Apr 20Apr 17Apr 14Apr 11Apr 6
20°FApr 24Apr 19Apr 16Apr 14Apr 11Apr 9Apr 6Apr 3Mar 31
16°FApr 16Apr 12Apr 9Apr 6Apr 4Apr 2Mar 31Mar 27Mar 21

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 8Sep 13Sep 17Sep 19Sep 23Sep 25Sep 28Oct 1Oct 5
32°FSep 18Sep 22Sep 26Sep 29Oct 1Oct 4Oct 7Oct 10Oct 16
28°FSep 29Oct 3Oct 6Oct 10Oct 13Oct 17Oct 20Oct 23Oct 28
24°FOct 10Oct 16Oct 21Oct 24Oct 27Oct 30Nov 1Nov 4Nov 9
20°FOct 21Oct 27Oct 31Nov 2Nov 5Nov 7Nov 10Nov 13Nov 19
16°FOct 30Nov 2Nov 6Nov 8Nov 11Nov 14Nov 17Nov 20Nov 24

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°F13613012412111711310910498
32°F161154149145140136131126120
28°F186179174169165160155150141
24°F207201196192188184180175168
20°F226219213210206203199194188
16°F240233228224221217213209203

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
9,115
Cooling degree days, base 65°F
255
Growing degree days, base 40°F
3,488
Growing degree days, base 45°F
2,576
Growing degree days, base 50°F
1,789
Growing degree days, base 55°F
1,129
Growing degree days, base 60°F
608

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,66900
February1,38900
March1,17802
April764018
May4107135
June15236339
July50110525
August6480481
September25421242
October647145
November1,05603
December1,48300

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 10.1 km from Proctor. 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 USW00014913 (Duluth). Public domain.