National Weather Service Weather Forecast Office

JACKSONVILLE, FLORIDA

THE WINTER OF 2009-2010… COLDEST SINCE THE WINTER OF
1977-1978 IN NORTHEAST FLORIDA AND SOUTHEAST GEORGIA

       The current cold spell across northeast Florida and southeast Georgia

marks the latest in a series of cold air outbreaks that has resulted in the

coldest winter across our area since the winter of 1977-1978. In Jacksonville, the

average temperature for the winter months…considered to be December through

February… was 51.1 degrees. This was 3.5 degrees colder than the long term

average…and the coldest winter since 1977-1978 which saw an average

temperature of 49.9 degrees.  As cold as this winter was… it only ranked as the

4th coldest Jacksonville winter on record. The coldest was a bone-chilling 48.9

degrees during the winter of 1976-1977, followed by the 49.9 of 1977-1978 and

50.2 in 1957-1958.  Not to be outdone, Gainesville’s winter average of 52.0

degrees tied the winter of 1962-1963 as their second coldest on record since

official records began in 1903… only slightly behind the 51.7 average in the winter

of 1963-1964.

Southeast Georgia also got in on the act with Alma recording their 5th coldest

winter…averaging 47.5 degrees… and Brunswick shivering through their 8th

coldest with an average of 49.7 degrees.

    The very cold average temperatures are even more remarkable

considering the first third of the winter…December 2009… was actually warmer

than normal in many areas… Jacksonville saw a relatively balmy average

December temperature of 56.3 degrees.  That was a full 1.3 degrees above

normal, and included a summer-like 84 degrees set as late as December 15th  … a

high of 73 on Christmas Day… and only 1 day with temperatures dipping to the

freezing mark...31 on Dec. 29th.  By contrast, January and February combined to

produce 21 days of freezing temperatures… and only one day warmer than 75… a

78 degree reading on January 24th.

    While it will be tempting for global warming skeptics to point to this winter

as an argument against the warming hypothesis… and equally tempting for

global warming enthusiasts to view it as validation that warming is producing

more of the extreme changes that climate change models suggest might occur in

a warming climate… the truth is more mundane.  A seasonal extreme such as we

have seen this winter is much more related to atmospheric oscillations that

operate on much shorter time frames and over relatively limited areas. In this

case, this winter was dominated by El Nino conditions which persisted through

the winter. El Nino winters are often cooler across the southeastern U.S. since El

Nino tends to shift the jet stream pattern farther southward… allowing more cold

fronts to pass and producing more clouds and precipitation that keep daytime

temperatures somewhat cooler.

    The winter of 2009-2010, however, saw an additional player enter the

 game… the North Atlantic Oscillation, or NAO.  When the NAO is in its negative

phase… as it has been almost constantly this winter… atmospheric

patterns tend to favor colder and stormier weather in the eastern United States.

Combined with El Nino, this has led to numerous low pressure centers passing

much farther south than usual, bringing frequent bouts of precipitation including

several severe weather outbreaks, with very cold air pouring southward in their

wake.  The same combination has been highly instrumental in producing the

crippling snowstorms experienced by much of the eastern U.S. this winter.  While

these conditions have been extremely obvious due to their impact on major

population centers in the eastern U.S., they mask the fact that for Earth as a

whole,  December 2009 was the 8th warmest December on record, while January

2010 was the 4th warmest.  

    As we head into spring, El Nino is forecast to gradually weaken, and longer

days and shorter nights will also contribute to gradually moderating

temperatures.  For the time being though… it is likely that our current

atmospheric patterns will produce at least a few more unpleasant parting winter

shots to continue to make this one of the more memorable winters in recent

memory across our area.