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Frost dates for Mason City, Iowa

In a typical year, Mason City’s last spring frost lands around Apr 29 and the first fall frost around Oct 7, a growing season of about 161 days. These are odds drawn from 30-year NOAA climate normals, not a promise. USDA zone 5a.

Right now the typical frost season has arrived; planting waits for spring.

Last spring frost and first fall frost odds for Mason City, Iowa
OddsLast spring frostFirst fall frost
10 percentApr 14Sep 25
50 percentApr 29Oct 7
90 percentMay 9Oct 21

A 10 percent year is an early year, a 90 percent year a late one. Frost-sensitive planting usually waits for the 90 percent side of the last-frost band.

Soil in Mason City is typically around 47°F at 4 inches this time of year, estimated from the last two weeks of normal air temperatures.

See what is plantable in your ZIP with the what-to-plant lookup.

Common questions

When is the last frost in Mason City, Iowa?

Mason City’s last spring frost falls around April 29 in a typical year. One year in ten it is done by April 14, and one year in ten frost holds on until May 9. Frost-sensitive planting usually waits for the late side of that band.

When is the first fall frost in Mason City?

The first fall frost arrives around October 7 in a typical year, as early as September 25 in an early year and as late as October 21 in a late one.

How long is the growing season in Mason City?

About 161 days, counted between the typical last spring frost and the typical first fall frost.

What USDA zone is Mason City in?

Mason City is in USDA hardiness zone 5a under the 2023 USDA Plant Hardiness Zone Map.

Dates come from 30-year NOAA climate normals for the nearest reporting station. They describe odds, not a forecast.

Nearby cities

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