Lead climate

Lead Frost Dates and Growing Season

NOAA 1991-2020 normals for Lead, 1.8 km from Lead, elevation 5112 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lead. 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 18 and the first fall freeze around September 29, a growing season of about 133 days.

Median at 36°F
last May 29, first September 21
Median at 32°F
last May 18, first September 29
Median at 28°F
last May 6, first October 7

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 14Jun 7Jun 3May 31May 29May 26May 23May 20May 17
32°FJun 1May 28May 24May 21May 18May 16May 12May 9May 5
28°FMay 21May 16May 13May 9May 6May 3May 1Apr 28Apr 22
24°FMay 9May 4May 1Apr 28Apr 25Apr 21Apr 18Apr 14Apr 9
20°FApr 29Apr 24Apr 19Apr 16Apr 13Apr 10Apr 7Apr 3Mar 28
16°FApr 20Apr 15Apr 11Apr 8Apr 4Apr 1Mar 27Mar 23Mar 15

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 7Sep 11Sep 14Sep 18Sep 21Sep 23Sep 25Sep 28Oct 2
32°FSep 15Sep 20Sep 24Sep 27Sep 29Oct 1Oct 4Oct 8Oct 13
28°FSep 23Sep 28Oct 1Oct 4Oct 7Oct 11Oct 15Oct 18Oct 23
24°FSep 30Oct 4Oct 9Oct 13Oct 16Oct 19Oct 23Oct 27Nov 1
20°FOct 7Oct 13Oct 17Oct 21Oct 24Oct 28Nov 1Nov 5Nov 10
16°FOct 15Oct 22Oct 27Oct 31Nov 3Nov 7Nov 10Nov 14Nov 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°F1301241191161121071039991
32°F153147141137133129124120112
28°F174168162158154149145139130
24°F197188183178173168164159151
20°F217209203197193188183178170
16°F240231224218213206201196188

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
7,206
Cooling degree days, base 65°F
425
Growing degree days, base 40°F
4,074
Growing degree days, base 45°F
3,028
Growing degree days, base 50°F
2,153
Growing degree days, base 55°F
1,428
Growing degree days, base 60°F
849

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,14701
February1,03002
March904013
April674039
May4148148
June14659372
July33163595
August47141561
September21149317
October583389
November879016
December1,13801

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 1.8 km from Lead. 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 USC00394834 (Lead). Public domain.