Buresh Blog: First frost & freeze of the season... Coldest nights zones... December averages

JACKSONVILLE, Fla. — The Atlantic hurricane season ends Nov. 30th: “Talking the Tropics With Mike”.

A Review of the 2023 Hurricane Season

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It’s that time of year - the first frost & freeze dates of the season. For Duval County, the first frost on avg. is Nov. 22, the first freeze avg. date is Dec. 6. Areas closer to the St. Johns River, Intracoastal & beaches will not typically see a frost or freeze until later in the year. Inland Duval Co. will have an avg. of 12-16 freezes per winter but that number is far less closer to the coast.

The USDA has updated their maps for “plant hardiness”.

PRISM, part of the OSU College of Engineering, stands for Parameter-elevation Regressions on Independent Slopes Model. The previous version of the plant hardiness map, also based on PRISM data, was released in January 2012.

The new plant hardiness map incorporates data from 13,412 weather stations, compared to the 7,983 that were used for the 2012 edition. Viewable in a Geographic Information System-based interactive format, the map is based on 30-year averages (1991 to 2020) for the lowest annual winter temperatures within specified locations. The 2012 edition was based on averages from 1976 to 2005.

Overall, the 2023 map is about 2.5 degrees warmer than the 2012 map across the conterminous United States. This translated into about half of the country shifting to a warmer 5-degree half zone, and half remaining in the same half zone. The central plains and Midwest generally warmed the most, with the southwestern U.S. warming very little.

Zone changes over the last 10 years - about a 5 degree F increase for much of the U.S. Lower 48:

JIA December averages: