Blue River Frost Dates and Growing Season

NOAA 1991-2020 normals for Climax, 14.3 km from Blue River, elevation 11345 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Climax. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

NOAA does not state freeze dates for this station.

Median at 28°F: last June 15, first September 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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	–	–	–	–	–	–	–	–	–
32°F	–	–	–	–	–	–	–	–	–
28°F	Jul 4	Jun 27	Jun 23	Jun 19	Jun 15	Jun 12	Jun 9	Jun 6	Jun 2
24°F	Jun 21	Jun 14	Jun 9	Jun 6	Jun 4	Jun 2	May 31	May 27	May 23
20°F	Jun 7	Jun 3	May 31	May 29	May 25	May 22	May 20	May 16	May 11
16°F	May 28	May 23	May 20	May 17	May 15	May 12	May 9	May 6	May 1

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	–	–	–	–	–	–	–	–	–
32°F	–	–	–	–	–	–	–	–	–
28°F	Aug 30	Sep 3	Sep 6	Sep 10	Sep 13	Sep 15	Sep 17	Sep 20	Sep 24
24°F	Sep 5	Sep 10	Sep 14	Sep 17	Sep 20	Sep 22	Sep 25	Sep 28	Oct 2
20°F	Sep 13	Sep 18	Sep 22	Sep 25	Sep 28	Sep 30	Oct 3	Oct 6	Oct 11
16°F	Sep 22	Sep 27	Sep 30	Oct 3	Oct 5	Oct 8	Oct 11	Oct 15	Oct 20

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	47	41	36	31	27	24	21	19	15
32°F	81	75	70	65	61	56	51	45	38
28°F	105	98	93	90	85	81	77	71	62
24°F	124	117	112	108	104	101	96	92	84
20°F	141	135	131	127	123	120	115	110	102
16°F	162	155	150	146	142	139	134	129	122

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: 11,932
Cooling degree days, base 65°F: 0
Growing degree days, base 40°F: 1,292
Growing degree days, base 45°F: 701
Growing degree days, base 50°F: 270
Growing degree days, base 55°F: 51
Growing degree days, base 60°F: 3

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Growing DD 50
January	1,556	0
February	1,371	0
March	1,338	0
April	1,120	0
May	877	2
June	519	45
July	360	124
August	419	78
September	600	21
October	966	0
November	1,253	0
December	1,555	0

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 14.3 km from Blue River. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00051660 (Climax). Public domain.