National Weather Service Weather Forecast Office

2010: A Year of Historical Climate Extremes in

Northeast Florida and Southeast Georgia

                From the continual arctic blasts of cold air to start the year, to the long standing oppressive heat of the summer, and the lack of any substantial rainfall during the latter half of the year, the weather in 2010 will be remembered mainly for the extreme variations in temperature and lack of precipitation that were experienced across northeast Florida and southeast Georgia.  Overall, despite a record summer heat wave, the quick return to much colder than normal weather in December will help make 2010 one of the coldest years on record across the region.  The climate records that are referenced in this report extend from 1871 to 2010 for Jacksonville, FL (JAX), from 1903 to 2010 for Gainesville, FL (GNV), and from 1948 to 2010 for both Alma, GA (AMG) and St Simons Island, GA (SSI).

                The cold start to 2010 can be partially explained by the dramatic shift in the mid-latitude jet stream configuration associated with the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO). These oscillations were in the negative phase and ended up as the most negative since records began in 1950. The switch began ironically on New Year’s Day as an arctic air mass entered the region and started what would be the coldest 2 weeks in climate history across the forecast area. Most of the climate sites across the area set new all-time records for consecutive days with minimum temperatures at 32 degrees or less.  Refer to Table 1 for more details.

                The cold start to 2010 not only set records in the first 2 weeks of January, it ended up being the coldest start to the first four months of the calendar year (January through April) of all-time at several climate locations in the region. See Table 2 for more details.

                The weather turned sharply warmer in May as it usually does in this region, due to a large ridge of high pressure that extended from the Western Atlantic Ocean across the southeast United States. This pattern remained in place over the entire summer season from May through September and was the cause of a heat wave that lasted longer than most ever have across the region.  Almost all of the climate sites in southeast Georgia and northeast Florida set new all-time consecutive day streaks of maximum temperatures greater than or equal to 90 degrees. See Table 3 for more details.

                Indian summer conditions persisted after the heat wave broke in August and lasted well into September.  Although no official statistics are kept on Heat Index values during the summer months, normally during June, July and August heat index values top out around 100 degrees each day, but this summer the lack of afternoon convection to cool temperatures off and the high levels of relative humidity allowed for the heat index to reach 105 degrees or more on 60 days this summer, while the heat index actually reached an extremely dangerous 110 degrees or more on 13 separate days this summer. In fact, the summer of 2010 (May through September) will go down as the warmest on record at most of our local climate locations.  See Table 4 for more details. 

                The early end to the wet season in September and the lack of any tropical cyclone activity moving towards the southeast U.S. allowed for yearly rainfall deficits to add up. Many locations went without any measurable rainfall in the month of October, including Jacksonville and Gainesville which set new monthly records for the lack of rainfall. In fact all the climate sites recorded almost a month long period without any measurable precipitation, Jacksonville 34 days, Gainesville 33 days, Alma 28 days and St Simons Island 25 days. The lack of rainfall due to the moderate to strong La Nina continued through the month of November and all the climate sites recorded one of driest autumns on record. See Table 5 for more details.

                The dry weather continued into December, but in addition to the severe drought conditions was the return to a negative phase in the (NAO) and (AO) which also allowed for early season arctic air masses to plunge into the region.  This will likely result in one of the coldest Decembers on record as average temperatures will run almost 10 degrees below normal.  Most of the climate locations in the region will also record over 15 to 20 calendar day freezes in the month of December.  More statements will be forthcoming on this cold end to the year on January 1^st.  Refer to Table 6 to see what new all-time records have already been broken for the greatest number of freezes in a calendar year.

                Yearly rainfall totals will range from about 10 to 25 inches below normal at most climate sites with St Simons Island, Georgia recording its driest year on record and much of the forecast area is under extreme drought conditions.  Yearly average temperatures will actually end up slightly below normal as the two seasonal extremes balance each other out, but the colder months have ended up with greater departures below normal. Refer to Table 7 for details.

Given the cold latter portion of the 2009-2010 winter and the near record cold we have seen in December, it is tempting to conclude that our area may be in for a brutally cold winter…but that is not necessarily the case. Most winter seasons see pattern shifts at some point, and recent events bear that out…December of 2009 was actually 1.4 degrees warmer than normal in Jacksonville with 10 days reaching 70 degrees or higher.  Despite the early season warmth, the rest of the winter turned abruptly colder, as noted in Table 2. A similar turnaround was noted in the winter of 1989-1990…after a record cold December averaging 7.7 degrees below normal, January and February turned almost balmy, averaging 4.4 and 6.5 degrees above normal, respectively.  The bottom line is that what happens early in a season is not necessarily an indicator of what the rest of the season will be like.

                The latest forecast from the Climate Prediction Center for the January through March calls for equal chances for either above or below normal temperatures…which often can indicate the likelihood of several pattern changes during the rest of the winter. The outlook also calls for a continuation of the drier than normal pattern the area has experienced the last several months.

Climate Prediction Center Website

http://www.cpc.ncep.noaa.gov/

If you have any questions and/or comments about the data presented in this report, please e-mail

Jason Hess - Climate Focal Point – jason.hess@noaa.gov

Steve Letro – Meteorologist-In-Charge – steve.letro@noaa.gov