Last and First Frost Dates in Iowa

The following chart is based on weather data collected from 1981 to 2010.* Probabilities indicate the likelihood of experiencing 32°F on or after the given date in spring and on or before the given date in fall.

Cities and towns listed are grouped by their location in the state from north to south. Within each group, cities are listed from west to east.

Date of First Freeze in Fall and Last Freeze in Spring

Location Date of first 32°F freeze in 10% of years Date of first 32°F freeze in 50% of years Date of first 32°F freeze in 90% of years Date of last 32°F freeze in 10% of years Date of last 32°F freeze in 50% of years Date of last 32°F freeze in 90% of years

Sioux Center

Sep. 19

Sep. 28

Oct. 8

Apr. 14

Apr. 28

May 14

Cherokee

Sep. 19

Sep. 26

Oct. 10

Apr. 18

May 1

May 16

Spirit Lake

Sep. 21

Oct. 3

Oct. 14

Apr. 8

Apr. 30

May 8

Mason City

Sep. 20

Oct. 3

Oct. 10

Apr. 19

May 3

May 16

New Hampton

Sep. 20

Oct. 2

Oct. 12

Apr. 10

Apr. 29

May 9

Fayette

Sep. 18

Sep. 29

Oct. 11

Apr. 17

May 6

May 21

Decorah

Sep. 21

Oct. 3

Oct. 13

Apr. 20

May 9

May 21

 

   

 

   

 

Sioux City

Sep. 20

Sep. 29

Oct. 13

Apr. 10

Apr. 26

May 11

Onawa

Sep. 20

Oct. 1

Oct. 14

Apr. 15

Apr. 28

May 10

Sac City

Sep. 20

Oct. 4

Oct. 17

Apr. 10

Apr. 26

May 10

Carroll

Sep. 18

Oct. 2

Oct. 10

Apr. 13

Apr. 27

May 10

Webster City

Sep. 18

Sep. 29

Oct. 10

Apr. 19

May 4

May 16

Ames

Sep. 23

Oct. 6

Oct. 21

Apr. 9

Apr. 20

May 6

Eldora

Sep. 25

Oct. 5

Oct. 17

Apr. 10

Apr. 23

May 8

Waterloo

Sep. 19

Sep. 29

Oct. 11

Apr. 15

Apr. 25

May 15

Cedar Rapids

Sep. 22

Oct. 5

Oct. 16

Apr. 9

Apr. 22

May 6

Manchester

Sep. 21

Sep. 30

Oct. 11

Apr. 18

May 2

May 14

Dubuque

Sep. 22

Oct. 5

Oct. 21

Apr. 9

Apr. 24

May 7

 

   

 

   

 

Council Bluffs

Sep. 23

Oct. 6

Oct. 24

Apr. 8

Apr. 22

May 7

Harlan

Sep. 22

Oct. 5

Oct. 24

Apr. 10

Apr. 24

May 9

Greenfield

Sep. 21

Oct. 6

Oct. 25

Apr. 9

Apr. 24

May 3

Des Moines

Sep. 26

Oct. 10

Oct. 27

Apr. 5

Apr. 18

Apr. 30

Grinnell

Sep. 16

Sep. 27

Oct. 10

Apr. 18

May 5

May 16

Sigourney

Oct. 1

1Oct. 2

Oct. 28

Apr. 5

Apr. 19

May 4

Washington

Sep. 22

Oct. 10

Oct. 21

Apr. 5

Apr. 17

May 5

Iowa City

Sep. 29

Oct. 13

Oct. 23

Mar. 31

Apr. 17

May 4

Le Claire

Oct. 3

Oct. 17

Nov. 2

28-Mar

Apr. 13

Apr. 27

Clinton

Sep. 22

Oct. 7

Oct. 19

Apr. 6

Apr. 19

May 6

 

   

 

   

 

Red Oak

Sep. 18

Oct. 4

Oct. 17

Apr. 10

Apr. 22

May 6

Beaconsfield

Sep. 23

Oct. 5

Oct. 27

Apr. 9

Apr. 20

May 2

Chariton

Sep. 20

Sep. 30

Oct. 14

Apr. 17

Apr. 30

May 17

Ottumwa

Sep. 25

Oct. 7

Oct. 28

Apr. 3

Apr. 17

May 3

Keosauqua

Sep. 21

Oct. 7

Oct. 21

Apr. 9

Apr. 18

May 3

Fairfield

Sep. 22

Oct. 10

Oct. 25

Apr. 5

Apr. 17

May 4

Mount Pleasant

Sep. 23

Oct. 11

Oct. 22

Apr. 5

Apr. 18

May 6

Fort Madison

Sep. 30

Oct. 19

Nov. 6

30-Mar

Apr. 8

Apr. 19

Burlington

Oct. 3

Oct. 18

Nov. 4

30-Mar

Apr. 14

May 1

* The data in this chart was provided by the Midwestern Regional Climate Center. Additional climatological information for the above locations and other sites in Iowa can be found at their website.

This article originally appeared in the 5/4/2005 issue. Updated 10/01/2021.

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