1-2 punch of freezes to blast Jacksonville

‘Advection freeze’ Tuesday morning followed by ‘radiational freeze’ Wednsday AM

Tuesday morning's freeze in first box is due to an advection freeze. Wednesday's freeze comes from radiation freeze (2nd box).

JACKSONVILLE, Fla. – The coldest air so far this season arrives Monday night/Tuesday morning in a one-two punch of freezes, each with hits own meteorological architecture, and that impacts how you should prepare.

The first freeze of 2020 is set to blast Northeast Florida and Southeast Georgia with the strength to zap life out of any plans that were thriving during the last few week’s unseasonably warm temperatures.

Recommended Videos



Officially, Jacksonville did have one freeze this season -- 31° on Dec. 3. But the next two mornings bring two types of freeze events: advection and radiation.

First up comes a dry, cold air mass that’s pouring into Florida with stiff northerly winds. The brute force of cold air flowing south brings what’s called an advection freeze. While it may only drop to 29° where the official temperature is measured at Jacksonville International Airport, it will feel much colder because of the wind.

Wednesday morning will drop below freezing but it will be a more common radiation freeze, which occurs on clear, calm nights when cold air settles at ground level while warm air “radiates” or escapes into the upper atmosphere. It won’t feel as cold, but the plants could still suffer.

The difference between the two results in different ways to prepare for the cold.

It is more difficult to protect plants from an advection freeze than a radiation freeze because strong winds can impact plant coverings. The body may need more layers of clothing and result in a colder “feel” due to wind chill.

One of Florida’s most brutal advection freezes wiped out citrus plants in 1835.

Author John Lee Williams’ account stated that “the northwest wind blew for 10 days and the temperature fell as low as -13.9 °C. Even the local river froze and all kinds of fruit trees were killed to the ground as far south as 28 °N latitude.”

Fortunately, major advection freeze events tend to be sporadic compared to radiation events.


About the Author:

After covering the weather from every corner of Florida and doing marine research in the Gulf, Mark Collins settled in Jacksonville to forecast weather for The First Coast.