Frost dates / Idaho / Twin Falls

Frost dates in Twin Falls, ID

The station on this page is TWIN FALLS-KMVT, ID US (USC00109293), 1.2 miles from the city point. Population in the Census 2024 estimate is 55,589.

Zone 7aUSDA average annual extreme minimum 0°F to 5°F, from ZIP 83328 (7.9 miles from the city point used on this page).

Median last 32°F is April 30. Median first 32°F is October 9. The 50% growing-season length is 161 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 17	Earlier date. A last 32°F on or after this day is common.
50%	April 30	Median.
10%	May 14	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%	September 24	Earlier date. A first 32°F on or before this day is uncommon.
50%	October 9	Median.
90%	October 24	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%	181
50%	161
90%	140

28°F threshold

	10%	50%	90%
Last, on or after	April 30	April 17	March 30
First, on or before	October 7	October 23	November 5
Season at least	211 days	187 days	166 days

36°F threshold

	10%	50%	90%
Last, on or after	June 2	May 14	May 1
First, on or before	September 12	September 28	October 12
Season at least	156 days	136 days	112 days

Station TWIN FALLS-KMVT, ID US (USC00109293). Completeness flag R, 15 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 1118.6 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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Twin Falls, ID

Zone 7aAverage annual extreme minimum 0°F to 5°F

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

Idaho. Nearest qualified station: TWIN FALLS-KMVT, ID US (USC00109293), 1.2 miles. Median last 32°F April 30. Median first 32°F October 9. The 50% growing-season length is 161 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	May 14	April 30	April 17
First 32°F on or before	September 24	October 9	October 24

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.

Date checks use your device’s calendar and appear after the page loads.