Truckee Frost Dates and Growing Season

NOAA 1991-2020 normals for Truckee RS, 1 km from Truckee, elevation 5823 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Truckee RS. 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 11, first September 17

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	Jun 30	Jun 24	Jun 18	Jun 15	Jun 11	Jun 9	Jun 5	Jun 2	May 26
24°F	Jun 9	Jun 1	May 27	May 20	May 13	May 7	May 3	Apr 30	Apr 24
20°F	May 8	May 1	Apr 27	Apr 23	Apr 19	Apr 16	Apr 12	Apr 9	Apr 5
16°F	Apr 25	Apr 18	Apr 13	Apr 9	Apr 6	Apr 2	Mar 29	Mar 23	Mar 13

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	Sep 3	Sep 7	Sep 10	Sep 14	Sep 17	Sep 20	Sep 23	Sep 27	Oct 3
24°F	Sep 16	Sep 23	Sep 28	Oct 1	Oct 4	Oct 9	Oct 13	Oct 17	Oct 25
20°F	Oct 6	Oct 14	Oct 18	Oct 22	Oct 26	Oct 29	Nov 1	Nov 5	Nov 10
16°F	Oct 23	Oct 31	Nov 3	Nov 5	Nov 9	Nov 12	Nov 16	Nov 19	Nov 23

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	39	35	30	27	24	21	18	15
32°F	83	76	70	66	59	54	48	42	35
28°F	118	110	106	100	95	90	85	80	71
24°F	168	159	153	147	141	136	128	122	111
20°F	208	200	194	189	185	180	174	169	160
16°F	242	233	227	221	215	210	206	200	190

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: 7,694
Cooling degree days, base 65°F: 63
Growing degree days, base 40°F: 2,943
Growing degree days, base 45°F: 1,993
Growing degree days, base 50°F: 1,240
Growing degree days, base 55°F: 658
Growing degree days, base 60°F: 257

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	1,118	0	0
February	951	0	0
March	918	0	0
April	750	0	5
May	532	0	64
June	294	3	188
July	109	34	392
August	116	25	375
September	297	2	182
October	588	0	34
November	869	0	0
December	1,154	0	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 1 km from Truckee. 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 USC00049043 (Truckee RS). Public domain.