Macy climate

Macy Frost Dates and Growing Season

NOAA 1991-2020 normals for Walthill 1E, 10.7 km from Macy, elevation 1280 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Walthill 1E. 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 1 and the first fall freeze around October 6, a growing season of about 156 days.

Median at 36°F
last May 8, first September 28
Median at 32°F
last May 1, first October 6
Median at 28°F
last April 21, first October 16

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 22May 17May 14May 11May 8May 6May 3Apr 30Apr 27
32°FMay 15May 10May 6May 3May 1Apr 29Apr 26Apr 22Apr 18
28°FMay 5May 1Apr 28Apr 24Apr 21Apr 19Apr 15Apr 12Apr 6
24°FApr 28Apr 22Apr 19Apr 16Apr 13Apr 9Apr 5Apr 2Mar 26
20°FApr 18Apr 14Apr 10Apr 6Apr 4Apr 1Mar 28Mar 22Mar 16
16°FApr 10Apr 5Apr 1Mar 29Mar 25Mar 20Mar 17Mar 13Mar 7

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 18Sep 22Sep 26Sep 28Oct 1Oct 3Oct 6Oct 10
32°FSep 20Sep 26Sep 30Oct 3Oct 6Oct 8Oct 11Oct 15Oct 19
28°FSep 30Oct 5Oct 9Oct 12Oct 16Oct 19Oct 21Oct 25Oct 29
24°FOct 11Oct 17Oct 21Oct 23Oct 25Oct 28Oct 31Nov 3Nov 7
20°FOct 20Oct 25Oct 29Nov 1Nov 3Nov 6Nov 8Nov 11Nov 17
16°FOct 28Nov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 21Nov 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°F159152148143140136132128120
32°F176169165161156152148143136
28°F196190185180176171167161154
24°F215207203199194191187181174
20°F235228223218213209205199193
16°F252245240235231227221215207

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
6,790
Cooling degree days, base 65°F
982
Growing degree days, base 40°F
5,326
Growing degree days, base 45°F
4,221
Growing degree days, base 50°F
3,234
Growing degree days, base 55°F
2,360
Growing degree days, base 60°F
1,608

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,38500
February1,13001
March883125
April4987106
May19164354
June22214642
July4328789
August13251704
September108105451
October44012147
November858016
December1,25800

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 10.7 km from Macy. 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 USC00258935 (Walthill 1E). Public domain.