Jackson County climate

Jackson County Frost Dates and Growing Season

NOAA 1991-2020 normals for Medford Rogue Vly AP, 13.1 km from Jackson County, elevation 1297 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Medford Rogue Vly AP. 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 8 and the first fall freeze around October 29, a growing season of about 204 days.

Median at 36°F
last April 30, first October 16
Median at 32°F
last April 8, first October 29
Median at 28°F
last March 10, first November 13

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 17May 10May 6May 3Apr 30Apr 28Apr 24Apr 19Apr 11
32°FApr 30Apr 23Apr 18Apr 12Apr 8Apr 3Mar 30Mar 25Mar 17
28°FApr 3Mar 27Mar 21Mar 15Mar 10Mar 5Feb 28Feb 23Feb 16
24°FMar 3Feb 25Feb 20Feb 16Feb 10Feb 2Jan 23Jan 11Dec 28
20°FFeb 9Jan 28Jan 17Jan 7Jan 1Dec 27Dec 21Dec 13Dec 2
16°FJan 13Jan 5Jan 1Dec 29Dec 25Dec 22Dec 16Dec 11Dec 4

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 3Oct 8Oct 11Oct 14Oct 16Oct 18Oct 21Oct 24Oct 29
32°FOct 14Oct 19Oct 23Oct 26Oct 29Oct 31Nov 4Nov 8Nov 16
28°FOct 26Oct 31Nov 4Nov 9Nov 13Nov 18Nov 24Dec 1Dec 9
24°FNov 7Nov 14Nov 22Nov 28Dec 3Dec 9Dec 17Dec 24Jan 7
20°FNov 15Nov 28Dec 3Dec 9Dec 15Dec 22Dec 29Jan 4Jan 20
16°FDec 1Dec 7Dec 11Dec 15Dec 20Dec 24Dec 29Jan 1Jan 10

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°F189182177172167164160154148
32°F232222215208204197192186176
28°F283268260253247240233225212
24°F343329319311302294285274262
20°F365365365361352345337331316
16°F365365365365365365365360344

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
97% of years
20°F or colder
66% of years
16°F or colder
24% 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
4,203
Cooling degree days, base 65°F
908
Growing degree days, base 40°F
6,023
Growing degree days, base 45°F
4,551
Growing degree days, base 50°F
3,326
Growing degree days, base 55°F
2,332
Growing degree days, base 60°F
1,536

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January76402
February587011
March518047
April3693125
May17937327
June55112507
July4317778
August3298759
September48131533
October28812209
November594024
December79504

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 13.1 km from Jackson County. 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 USW00024225 (Medford Rogue Vly AP). Public domain.