Frost dates / Idaho / Post Falls

Frost dates in Post Falls, ID

The station on this page is COEUR D'ALENE, ID US (USC00101956), 7.5 miles from the city point. Population in the Census 2024 estimate is 45,800.

Zone 6bUSDA average annual extreme minimum -5°F to 0°F, from ZIP 83854 (1.5 miles from the city point used on this page).

Median last 32°F is April 22. Median first 32°F is October 18. The 50% growing-season length is 179 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Last 32°F in spring

NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.

Probability	Date	How to read it
90%	April 4	Earlier date. A last 32°F on or after this day is common.
50%	April 22	Median.
10%	May 6	Later date. A last 32°F on or after this day is uncommon.

First 32°F in fall

NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.

Probability	Date	How to read it
10%	October 4	Earlier date. A first 32°F on or before this day is uncommon.
50%	October 18	Median.
90%	November 5	Later date. A first 32°F on or before this day is common.

32°F growing-season length

Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.

Probability the season is at least this long	Days
10%	202
50%	179
90%	158

28°F threshold

	10%	50%	90%
Last, on or after	April 21	April 1	March 13
First, on or before	October 15	November 1	November 20
Season at least	238 days	214 days	189 days

36°F threshold

	10%	50%	90%
Last, on or after	May 21	May 7	April 25
First, on or before	September 23	October 6	October 21
Season at least	171 days	151 days	130 days

Station COEUR D'ALENE, ID US (USC00101956). Completeness flag R, 24 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 100%. Freeze dates are conditional on that threshold occurring. Elevation 650.1 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

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Post Falls, ID

Zone 6bAverage annual extreme minimum -5°F to 0°F

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Idaho. Nearest qualified station: COEUR D'ALENE, ID US (USC00101956), 7.5 miles. Median last 32°F April 22. Median first 32°F October 18. The 50% growing-season length is 179 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	May 6	April 22	April 4
First 32°F on or before	October 4	October 18	November 5

Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.

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Planting calendar

Frost dates for Idaho are above. Planting windows appear for states with a cited extension guide. The fall and seed tools use the numbers you enter and the station dates.

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