Rangely climate

Rangely Frost Dates and Growing Season

NOAA 1991-2020 normals for Rangely 1E, 2.7 km from Rangely, elevation 5277 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rangely 1E. 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 15 and the first fall freeze around October 1, a growing season of about 136 days.

Median at 36°F
last May 28, first September 23
Median at 32°F
last May 15, first October 1
Median at 28°F
last May 3, first October 10

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 13Jun 7Jun 3May 31May 28May 25May 22May 19May 15
32°FJun 2May 27May 23May 18May 15May 13May 10May 6May 2
28°FMay 17May 12May 8May 5May 3Apr 30Apr 28Apr 24Apr 20
24°FMay 5Apr 30Apr 26Apr 22Apr 19Apr 16Apr 13Apr 9Apr 4
20°FApr 21Apr 16Apr 13Apr 9Apr 5Apr 2Mar 31Mar 24Mar 16
16°FApr 9Apr 3Mar 31Mar 25Mar 20Mar 16Mar 12Mar 8Mar 3

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 10Sep 15Sep 17Sep 21Sep 23Sep 25Sep 27Sep 30Oct 4
32°FSep 19Sep 23Sep 25Sep 28Oct 1Oct 3Oct 5Oct 8Oct 12
28°FSep 26Oct 1Oct 4Oct 7Oct 10Oct 12Oct 15Oct 17Oct 21
24°FOct 5Oct 11Oct 15Oct 17Oct 20Oct 22Oct 25Oct 28Nov 1
20°FOct 16Oct 21Oct 25Oct 27Oct 30Nov 1Nov 4Nov 7Nov 11
16°FOct 25Oct 31Nov 2Nov 6Nov 8Nov 11Nov 14Nov 17Nov 21

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°F13512812312011511110710294
32°F154148143139136132127123115
28°F178170166161157154150145140
24°F202195190185181177172168160
20°F227219214209205200195191185
16°F253245239235230225220214205

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
7,354
Cooling degree days, base 65°F
658
Growing degree days, base 40°F
4,616
Growing degree days, base 45°F
3,560
Growing degree days, base 50°F
2,640
Growing degree days, base 55°F
1,852
Growing degree days, base 60°F
1,192

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,49300
February1,12400
March82905
April560045
May28212228
June60117508
July3281742
August8210667
September12939368
October518075
November94402
December1,40600

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 2.7 km from Rangely. 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 USC00056832 (Rangely 1E). Public domain.