Coastal and Marine Impacts from Imelda and Humberto as Both Track Away from the Southeast U.S.

Swells and high surf from both Imelda and Humberto are expected to bring dangerous marine and rip current conditions to the east coast of Florida and Georgia today, spreading north along much of the east coast of the U.S. this week. Heavy rainfall north and west of Imelda falling across coastal Florida and Georgia into the Carolinas could cause isolated flash and urban flooding through Tuesday. Read More >

A question we are often asked is "By what date does my town typically get its first freeze?" The charts and maps below will help answer that question for a number of locations across western South Dakota.

The charts below show the percentage of past years in which the first frost (36º F) or freeze (32º F or below) occurred by a specific date. For example, in 90% of past years, Rapid City first reached 32º F by October 12. In half of the past years, Rapid City reached 28ºF by October 9th.

The regional maps farther down show the average date of the first freeze (32º F) and hard freeze (28º F).

A special thanks to the former South Dakota State Climatologist, Dennis Todey for the data in the charts. More percentiles and locations can be found at South Dakota State University's Climate Page.

Rapid City	36º F	32º F	28º F	24º F
90%	Sep 30	Oct 12	Oct 25	Nov 8
50%	Sep 20	Sep 26	Oct 9	Oct 18
10%	Sep 10	Sep 13	Sep 23	Sep 27

Lead	36º F	32º F	28º F	24º F
90%	Sep 22	Oct 4	Oct 22	Oct 31
50%	Sep 12	Sep 20	Oct 1	Oct 11
10%	Aug 22	Sep 8	Sep 14	Sep 24

Custer	36º F	32º F	28º F	24º F
90%	Sep 15	Sep 22	Oct 6	Oct 18
50%	Aug 18	Sep 9	Sep 17	Sep 28
10%	Jul 1	Aug 8	Sep 2	Sep 10

Faith	36º F	32º F	28º F	24º F
90%	Oct 2	Oct 11	Oct 24	Nov 3
50%	Sep 21	Sep 26	Oct 7	Oct 18
10%	Sep 9	Sep 13	Sep 23	Sep 26

Camp Crook	36º F	32º F	28º F	24º F
90%	Sep 18	Sep 27	Oct 7	Oct 19
50%	Sep 3	Sep 15	Sep 23	Oct 4
10%	Jul 28	Sep 1	Sep 10	Sep 16

Maps: Median Date for first freeze (32º F) and hard freeze (28º F).

A special thanks to the Midwestern Regional Climate Center for these maps.

UNR RSS Feed

Coastal and Marine Impacts from Imelda and Humberto as Both Track Away from the Southeast U.S.

Average First Fall Frost / Freeze Date Probabilities

Maps: Median Date for first freeze (32º F) and hard freeze (28º F).