Meridian climate

Meridian Frost Dates and Growing Season

NOAA 1991-2020 normals for Whitney Dam, 27.5 km from Meridian, elevation 574 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Whitney Dam. 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 15 and the first fall freeze around November 14, a growing season of about 243 days.

Median at 36°F
last April 1, first November 4
Median at 32°F
last March 15, first November 14
Median at 28°F
last March 2, first November 28

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 20Apr 13Apr 8Apr 4Apr 1Mar 28Mar 22Mar 17Mar 8
32°FApr 7Mar 31Mar 25Mar 19Mar 15Mar 10Mar 6Mar 2Feb 25
28°FMar 28Mar 17Mar 11Mar 6Mar 2Feb 26Feb 21Feb 16Feb 6
24°FMar 13Mar 3Feb 25Feb 17Feb 10Feb 4Jan 30Jan 23Jan 11
20°FMar 1Feb 14Feb 5Jan 31Jan 25Jan 17Jan 10Dec 31Dec 22
16°FFeb 9Feb 1Jan 28Jan 20Jan 14Jan 9Jan 4Dec 31Dec 23

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 23Oct 28Oct 31Nov 2Nov 4Nov 7Nov 11Nov 16Nov 21
32°FOct 31Nov 3Nov 7Nov 11Nov 14Nov 18Nov 22Nov 28Dec 3
28°FNov 6Nov 13Nov 18Nov 23Nov 28Dec 2Dec 5Dec 10Dec 20
24°FNov 17Nov 25Dec 1Dec 6Dec 11Dec 19Dec 26Jan 1Jan 12
20°FDec 2Dec 11Dec 19Dec 25Dec 31Jan 3Jan 8Jan 16Feb 1
16°FDec 19Dec 25Dec 31Jan 3Jan 6Jan 10Jan 17Jan 24Feb 2

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°F245238231224219213208203194
32°F271262254249243238232225215
28°F304290283277271265258251241
24°F341331321312305298289278267
20°F365365358350343335330318303
16°F365365365365365365360351338

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
99% of years
20°F or colder
78% of years
16°F or colder
38% 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
2,343
Cooling degree days, base 65°F
2,537
Growing degree days, base 40°F
9,435
Growing degree days, base 45°F
7,771
Growing degree days, base 50°F
6,231
Growing degree days, base 55°F
4,844
Growing degree days, base 60°F
3,607

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January603163
February441499
March27525257
April10487439
May13264716
June0461910
July05751,040
August05801,044
September4380826
October74135529
November29422227
December536381

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 27.5 km from Meridian. 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 USC00419715 (Whitney Dam). Public domain.