When is the first frost in Des Moines? The Old Farmer's Almanac says chilly days are near

With the first day of fall behind us, the first frost is the next indicator for Iowans to prepare for the upcoming winter.

The Old Farmer's Almanac predicts when the first and last frost of the year will be. Some towns in Iowa already have passed the estimated frost dates. In other cities, like Des Moines, residents still have time for last-minute gardening before temperatures begin to drop.

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How does the Old Farmer's Almanac predict the first and last frost?

Frost dates are estimates based on historical climate data. These dates are not set in stone, according to the Old Farmer's Almanac . There is a 30% chance that frost can occur after the spring frost date or before the fall frost date.

Frost is typically predicted when air temperatures hit 32 degrees. However, that doesn't mean frost can't occur when the temperature is just above freezing. Weather, topography and microclimates also can create variation in the occurrence of frost .

What classifies as the frost dates, according to the Old Farmer's Almanac?

Frost dates are determined by the average date of the last light freeze in the spring or the first light freeze in the fall. There are three classifications of freeze temperatures based on the impacts on plants, according to the Old Farmer's Almanac .

A light freeze can occur when temperatures range from 29 degrees to 32 degrees. This usually kills tender plants. Moderate freezes happen when temperatures range from 25 degrees to 28 degrees, which is widely destructive to most vegetation. Severe freezes cause heavy damage to most garden plants and occurs when the temperatures drop to 24 degrees and colder.

When will first and last frosts occur around Iowa?

The following information includes estimates for the first fall frost and spring frost around Iowa, according to the Old Farmer's Almanac . The calculations are based on data from the National Oceanic and Atmospheric Administration and can vary depending on environmental conditions of the specific location.

• Ames — First fall frost Oct. 2 and last spring frost May 2.
• Burlington — First fall frost Oct. 15 and last spring frost April 22.
• Des Moines — First fall frost Oct. 14 and last spring frost April 24.
• Iowa City — First fall frost Oct.13 and last spring frost April 28.
• Sioux City — First fall frost Oct. 1 and last spring frost May 4

Are there any low temperatures in the forecast?

The National Weather Service in Des Moines says temperatures may drop on Monday "with several nights of near to below freezing lows early next week."

Des Moines could drop to 33 degrees, while Mason City could see 27.

Kate Kealey is a general assignment reporter for the Des Moines Register. Reach her at kkealey@registermedia.com or follow her on Twitter at @Kkealey17 .

This article originally appeared on Des Moines Register: When is the first frost in Des Moines? The Old Farmer's Almanac says chilly days are near