Boyden climate

Boyden Frost Dates and Growing Season

NOAA 1991-2020 normals for Sheldon, 12.4 km from Boyden, elevation 1420 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sheldon. 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 5 and the first fall freeze around September 28, a growing season of about 145 days.

Median at 36°F
last May 13, first September 20
Median at 32°F
last May 5, first September 28
Median at 28°F
last April 28, first October 6

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 25May 21May 18May 16May 13May 10May 8May 4May 1
32°FMay 18May 13May 9May 7May 5May 3May 1Apr 28Apr 24
28°FMay 9May 5May 2Apr 30Apr 28Apr 25Apr 22Apr 19Apr 15
24°FMay 1Apr 27Apr 24Apr 21Apr 18Apr 15Apr 12Apr 8Apr 3
20°FApr 23Apr 18Apr 15Apr 11Apr 8Apr 4Apr 2Mar 29Mar 22
16°FApr 16Apr 10Apr 6Apr 3Mar 31Mar 27Mar 22Mar 18Mar 13

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 8Sep 12Sep 15Sep 18Sep 20Sep 23Sep 26Oct 1Oct 4
32°FSep 14Sep 19Sep 23Sep 26Sep 28Oct 1Oct 3Oct 7Oct 12
28°FSep 23Sep 27Sep 30Oct 3Oct 6Oct 10Oct 14Oct 16Oct 21
24°FOct 1Oct 6Oct 12Oct 15Oct 19Oct 21Oct 24Oct 26Oct 31
20°FOct 15Oct 20Oct 23Oct 25Oct 28Oct 30Nov 1Nov 4Nov 8
16°FOct 22Oct 27Oct 31Nov 1Nov 4Nov 7Nov 10Nov 14Nov 19

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°F148142137133130126123119113
32°F162156152149145142138134128
28°F180174169165161157154149143
24°F203195190185181177173168161
20°F223215209205201196192187181
16°F240232226220216212208203195

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
7,900
Cooling degree days, base 65°F
607
Growing degree days, base 40°F
4,493
Growing degree days, base 45°F
3,477
Growing degree days, base 50°F
2,576
Growing degree days, base 55°F
1,795
Growing degree days, base 60°F
1,134

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,55300
February1,28000
March1,026010
April611257
May26636268
June46142546
July13216668
August31152586
September17554343
October547692
November96807
December1,38600

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 12.4 km from Boyden. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00137594 (Sheldon). Public domain.