Milton climate

Milton Frost Dates and Growing Season

NOAA 1991-2020 normals for Tacoma #1, 7.5 km from Milton, elevation 25 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tacoma #1. 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 March 8 and the first fall freeze around November 14, a growing season of about 250 days.

Median at 36°F
last April 2, first October 31
Median at 32°F
last March 8, first November 14
Median at 28°F
last February 11, first December 1

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°FApr 24Apr 16Apr 11Apr 6Apr 2Mar 31Mar 27Mar 22Mar 13
32°FMar 31Mar 23Mar 17Mar 12Mar 8Mar 3Feb 28Feb 23Feb 15
28°FMar 4Feb 27Feb 23Feb 17Feb 11Feb 3Jan 26Jan 12Dec 29
24°FFeb 18Feb 10Jan 31Jan 19Jan 7Dec 31Dec 21Dec 12Dec 2
20°FFeb 10Jan 27Jan 4Dec 28Dec 19Dec 13Dec 8Dec 5Nov 29
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.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 16Oct 21Oct 25Oct 28Oct 31Nov 2Nov 6Nov 10Nov 15
32°FOct 30Nov 3Nov 7Nov 11Nov 14Nov 17Nov 21Nov 26Dec 2
28°FNov 8Nov 15Nov 20Nov 25Dec 1Dec 5Dec 11Dec 22Jan 1
24°FNov 20Nov 29Dec 5Dec 11Dec 17Dec 24Dec 31Jan 7Feb 2
20°FNov 27Dec 2Dec 7Dec 11Dec 14Dec 24Jan 1Jan 14Feb 10
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.

Threshold10%20%30%40%50%60%70%80%90%
36°F233224218213209204199193185
32°F283270262256250244238231223
28°F338326316309301292283274264
24°F365365364354343334328318307
20°F365365365365365365365349334
16°F365365365365365365365365365

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
99% of years
24°F or colder
72% of years
20°F or colder
25% of years
16°F or colder
4% 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
4,332
Cooling degree days, base 65°F
211
Growing degree days, base 40°F
5,118
Growing degree days, base 45°F
3,564
Growing degree days, base 50°F
2,306
Growing degree days, base 55°F
1,359
Growing degree days, base 60°F
656

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January69005
February59206
March546027
April398084
May2296244
June10624368
July2284527
August2181525
September11116356
October3520136
November557025
December71004

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 7.5 km from Milton. 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 USC00458278 (Tacoma #1). Public domain.