Glendale Frost Dates and Growing Season

NOAA 1991-2020 normals for Youngtown, 12.4 km from Glendale, elevation 1135 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Youngtown. 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 January 20 and the first fall freeze around December 15, a growing season of about 331 days.

Median at 36°F: last February 14, first December 2
Median at 32°F: last January 20, first December 15
Median at 28°F: last January 3, first December 29

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	Mar 4	Feb 28	Feb 23	Feb 18	Feb 14	Feb 9	Feb 4	Jan 31	Jan 21
32°F	Feb 18	Feb 9	Feb 2	Jan 28	Jan 20	Jan 13	Jan 6	Dec 31	Dec 23
28°F	Feb 1	Jan 18	Jan 12	Jan 8	Jan 3	Dec 31	Dec 27	Dec 19	Dec 13
24°F	–	–	–	–	–	–	–	–	–
20°F	–	–	–	–	–	–	–	–	–
16°F	–	–	–	–	–	–	–	–	–

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	Nov 17	Nov 23	Nov 26	Nov 29	Dec 2	Dec 5	Dec 8	Dec 12	Dec 18
32°F	Nov 28	Dec 3	Dec 8	Dec 11	Dec 15	Dec 19	Dec 23	Dec 28	Jan 7
28°F	Dec 10	Dec 14	Dec 18	Dec 23	Dec 29	Jan 1	Jan 5	Jan 10	Jan 22
24°F	–	–	–	–	–	–	–	–	–
20°F	–	–	–	–	–	–	–	–	–
16°F	–	–	–	–	–	–	–	–	–

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	319	309	302	296	291	285	280	274	265
32°F	358	349	342	337	331	324	316	307	297
28°F	365	365	365	365	365	360	353	345	334
24°F	365	365	365	365	365	365	365	365	365
20°F	365	365	365	365	365	365	365	365	365
16°F	365	365	365	365	365	365	365	365	365

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: 95% of years
28°F or colder: 49% of years
24°F or colder: 6% of years
20°F or colder: 0% of years
16°F or colder: 0% 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: 1,334
Cooling degree days, base 65°F: 3,872
Growing degree days, base 40°F: 11,664
Growing degree days, base 45°F: 9,853
Growing degree days, base 50°F: 8,100
Growing degree days, base 55°F: 6,490
Growing degree days, base 60°F: 5,083

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	365	0	129
February	245	3	191
March	118	47	395
April	29	162	584
May	2	413	876
June	0	666	1,116
July	0	846	1,311
August	0	818	1,283
September	0	614	1,063
October	13	268	721
November	160	34	328
December	403	0	102

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 12.4 km from Glendale. 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 USC00029634 (Youngtown). Public domain.