North Reading climate

North Reading Frost Dates and Growing Season

NOAA 1991-2020 normals for Middleton, 5.3 km from North Reading, elevation 110 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Middleton. 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 3 and the first fall freeze around October 9, a growing season of about 157 days.

Median at 36°F
last May 17, first October 1
Median at 32°F
last May 3, first October 9
Median at 28°F
last April 21, first October 21

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 29May 25May 22May 19May 17May 13May 9May 5May 2
32°FMay 20May 14May 9May 6May 3May 1Apr 28Apr 25Apr 20
28°FMay 6May 1Apr 27Apr 24Apr 21Apr 18Apr 16Apr 11Apr 7
24°FApr 20Apr 15Apr 12Apr 9Apr 6Apr 4Apr 2Mar 31Mar 26
20°FApr 9Apr 4Apr 2Mar 31Mar 29Mar 26Mar 22Mar 18Mar 13
16°FMar 31Mar 29Mar 25Mar 22Mar 18Mar 15Mar 13Mar 9Mar 6

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 18Sep 23Sep 26Sep 29Oct 1Oct 2Oct 5Oct 7Oct 12
32°FSep 29Oct 2Oct 4Oct 7Oct 9Oct 12Oct 15Oct 18Oct 24
28°FOct 6Oct 11Oct 15Oct 19Oct 21Oct 24Oct 27Oct 31Nov 4
24°FOct 21Oct 26Oct 29Nov 1Nov 3Nov 6Nov 9Nov 13Nov 19
20°FNov 1Nov 5Nov 8Nov 12Nov 15Nov 18Nov 23Nov 27Dec 2
16°FNov 13Nov 18Nov 23Nov 26Nov 30Dec 2Dec 5Dec 9Dec 17

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°F154149144141137133129124119
32°F177170165161157154150145138
28°F201195190186182177173167159
24°F230222217213209206201197190
20°F255247242236231227223218213
16°F278271265260255250246241233

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
6,554
Cooling degree days, base 65°F
496
Growing degree days, base 40°F
4,526
Growing degree days, base 45°F
3,426
Growing degree days, base 50°F
2,473
Growing degree days, base 55°F
1,666
Growing degree days, base 60°F
1,004

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22301
February1,04700
March94908
April588354
May29617213
June8482450
July13186639
August18150597
September13453373
October4354115
November726022
December1,04202

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 5.3 km from North Reading. 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 USC00194744 (Middleton). Public domain.