Del Norte climate

Del Norte Frost Dates and Growing Season

NOAA 1991-2020 normals for Del Norte 3ENE, 4.2 km from Del Norte, elevation 7846 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Del Norte 3ENE. 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 23 and the first fall freeze around September 25, a growing season of about 123 days.

Median at 36°F
last June 6, first September 17
Median at 32°F
last May 23, first September 25
Median at 28°F
last May 9, 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 19Jun 15Jun 12Jun 8Jun 6Jun 4Jun 2May 29May 24
32°FJun 8Jun 3May 31May 26May 23May 21May 18May 15May 11
28°FMay 26May 19May 15May 12May 9May 7May 4May 2Apr 28
24°FMay 12May 6May 3May 1Apr 28Apr 26Apr 22Apr 20Apr 15
20°FApr 30Apr 25Apr 22Apr 19Apr 16Apr 14Apr 11Apr 7Apr 3
16°FApr 20Apr 15Apr 11Apr 8Apr 5Apr 2Mar 31Mar 25Mar 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 6Sep 10Sep 13Sep 15Sep 17Sep 19Sep 21Sep 23Sep 26
32°FSep 13Sep 18Sep 21Sep 23Sep 25Sep 27Sep 30Oct 3Oct 7
28°FSep 21Sep 25Sep 29Oct 1Oct 4Oct 6Oct 9Oct 13Oct 17
24°FSep 29Oct 3Oct 6Oct 9Oct 13Oct 15Oct 18Oct 21Oct 26
20°FOct 9Oct 14Oct 18Oct 20Oct 23Oct 26Oct 30Nov 1Nov 5
16°FOct 19Oct 23Oct 27Oct 31Nov 2Nov 5Nov 8Nov 11Nov 15

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°F11611110710410198948985
32°F141135131127123119115110103
28°F164158153150145142138132125
24°F184179174170166163159153146
20°F207202197192189185180174167
16°F232224218214210206201197190

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
7,753
Cooling degree days, base 65°F
81
Growing degree days, base 40°F
3,444
Growing degree days, base 45°F
2,434
Growing degree days, base 50°F
1,586
Growing degree days, base 55°F
894
Growing degree days, base 60°F
381

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,36700
February1,07700
March89801
April650015
May4000118
June14513320
July4041467
August7124419
September2542211
October583036
November95700
December1,31300

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 4.2 km from Del Norte. 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 USC00052184 (Del Norte 3ENE). Public domain.