Amboy climate

Amboy Frost Dates and Growing Season

NOAA 1991-2020 normals for Dixon 1W, 20.4 km from Amboy, elevation 660 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Dixon 1W. 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 April 21 and the first fall freeze around October 19, a growing season of about 180 days.

Median at 36°F
last May 2, first October 9
Median at 32°F
last April 21, first October 19
Median at 28°F
last April 10, first October 30

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 16May 11May 7May 4May 2Apr 29Apr 26Apr 22Apr 18
32°FMay 5May 1Apr 28Apr 24Apr 21Apr 18Apr 15Apr 11Apr 7
28°FApr 26Apr 21Apr 16Apr 13Apr 10Apr 8Apr 5Apr 2Mar 27
24°FApr 14Apr 9Apr 6Apr 3Apr 1Mar 29Mar 25Mar 20Mar 15
20°FApr 3Mar 31Mar 27Mar 22Mar 19Mar 17Mar 14Mar 10Mar 5
16°FMar 25Mar 20Mar 17Mar 14Mar 11Mar 8Mar 5Mar 2Feb 26

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 24Sep 29Oct 3Oct 5Oct 9Oct 12Oct 15Oct 18Oct 22
32°FOct 4Oct 10Oct 14Oct 16Oct 19Oct 21Oct 24Oct 26Oct 30
28°FOct 17Oct 22Oct 25Oct 27Oct 30Nov 1Nov 3Nov 7Nov 12
24°FOct 28Nov 1Nov 3Nov 6Nov 8Nov 11Nov 14Nov 18Nov 22
20°FNov 4Nov 8Nov 11Nov 15Nov 17Nov 20Nov 23Nov 27Dec 3
16°FNov 10Nov 15Nov 19Nov 23Nov 26Nov 29Dec 1Dec 6Dec 13

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°F178171166161158154150145138
32°F200192188184180176172166158
28°F220214209205201198193188181
24°F244236231226221217214209203
20°F264257251246242238233228222
16°F282274268265260255250245239

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
6,487
Cooling degree days, base 65°F
852
Growing degree days, base 40°F
5,262
Growing degree days, base 45°F
4,133
Growing degree days, base 50°F
3,126
Growing degree days, base 55°F
2,240
Growing degree days, base 60°F
1,481

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,35500
February1,10701
March860126
April4767107
May18960348
June30188607
July4267728
August9223679
September10793441
October40413160
November779025
December1,16902

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 20.4 km from Amboy. 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 USC00112348 (Dixon 1W). Public domain.