Manly climate

Manly Frost Dates and Growing Season

NOAA 1991-2020 normals for Northwood, 17 km from Manly, elevation 1190 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Northwood. 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 4 and the first fall freeze around October 4, a growing season of about 152 days.

Median at 36°F
last May 13, first September 25
Median at 32°F
last May 4, first October 4
Median at 28°F
last April 24, first October 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.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 27May 22May 18May 15May 13May 10May 8May 5May 1
32°FMay 16May 12May 9May 6May 4May 2Apr 29Apr 25Apr 21
28°FMay 7May 2Apr 30Apr 26Apr 24Apr 21Apr 17Apr 14Apr 9
24°FApr 28Apr 23Apr 20Apr 16Apr 14Apr 10Apr 8Apr 5Apr 1
20°FApr 20Apr 14Apr 10Apr 7Apr 4Apr 2Mar 31Mar 27Mar 20
16°FApr 12Apr 6Apr 3Mar 31Mar 29Mar 25Mar 21Mar 17Mar 12

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 13Sep 17Sep 20Sep 23Sep 25Sep 28Oct 1Oct 4Oct 7
32°FSep 20Sep 25Sep 28Oct 1Oct 4Oct 6Oct 9Oct 12Oct 17
28°FOct 1Oct 5Oct 8Oct 11Oct 13Oct 16Oct 19Oct 21Oct 25
24°FOct 10Oct 15Oct 18Oct 20Oct 22Oct 25Oct 27Oct 31Nov 4
20°FOct 19Oct 24Oct 27Oct 30Nov 1Nov 3Nov 6Nov 10Nov 16
16°FOct 31Nov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 20Nov 26

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°F151145140137133130126122116
32°F169162158154152148144140135
28°F190184179176172167163159153
24°F209203199195191188184180173
20°F230221216213208205201197191
16°F247240235230227223218214206

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
8,378
Cooling degree days, base 65°F
392
Growing degree days, base 40°F
4,071
Growing degree days, base 45°F
3,091
Growing degree days, base 50°F
2,225
Growing degree days, base 55°F
1,479
Growing degree days, base 60°F
858

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,62600
February1,34800
March1,10107
April652145
May31221216
June6795479
July22146589
August4793511
September20333298
October589373
November99906
December1,41400

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 17 km from Manly. 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 USC00136103 (Northwood). Public domain.