Warm, Dry October May Foretell the Winter

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- Temperatures were above normal in nearly all of Florida during October

- Drought conditions have developed in areas not affected by Hurricane Matthew

- Warm and dry trend (compared to normal) may continue through winter

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October was unusually warm in Florida.  Nearly all reporting stations recorded above normal temperatures, some even landing in the top ten. Rainfall, however, varied greatly by location, and this was largely a result of Hurricane Matthew. Even still, more than half of the state recorded less rainfall than normal.  Excluding hurricane activity, the warm and dry trend may last through early spring, especially if La Nina conditions develop.

Top Ten Warm Octobers

The Florida Climate Center published a report Wednesday that detailed just how warm the month was across the state. October 2016 was the 5th warmest on record in Miami, 6th warmest in Pensacola, 8th for Tampa, and 9th for Tallahassee. In addition to the month as a whole, 15 daily warm weather records were either tied or broken.

Drought to Deluge Along I-10

A graphical depiction of the monthly rainfall departure from normal (inches) for October is given in the figure below (courtesy of NOAA, NWS).

Regarding rainfall, it was a story of the “haves and have nots”. Areas that were directly affected by Hurricane Matthew received near or above normal precipitation, which contrasts greatly with locations that didn’t. For example, a trip along I-10 would take you from land that hasn’t received a drop to rain in more than 35 days, such as in Pensacola, to where nearly ten inches of water fell over a 30-day period in the Jacksonville metro.  Some areas near Florida’s First Coast ended the month with a surplus of more than five inches compared to normal.

La Nina Winter Possible

October is typically a much drier month in Florida, as this is usually when the rainy season ends. It’s also still quite warm this time of year since cold fronts don’t frequent the state as often as they do in the winter months.

However, David Zierden, State Climatologist at Florida State University, says there may be an explanation for the more extreme conditions.

“It’s well known that this pattern usually starts setting in during the early fall, but the abnormally warm, dry weather is more consistent with what we would expect in a La Nina.”

The La Nina David speaks of, which is an abnormal cooling of the central Pacific Ocean waters, is projected by NOAA to develop during the winter months. This is a reversal of the more recent El Nino that was to blame for the wet and stormy weather many Floridians may remember from the winter of 2015-16.

David says the impact of La Nina is likely to intensify and expand over the winter months across the rest of the state.

“We’re coming up on the dry season anyway, but during a La Nina the rest of the peninsula only receives about half of normal rainfall, and temperatures generally run between two to four degrees above normal.”

Reality Check This Weekend

The recent warmth will come to an end across much of the state this weekend with the passage of a strong cold front. Even still, temperatures are only likely to return to normal values for this time of year, then potentially warm back above normal next week. And keeping with the going trends, little or no rain is expected with this weekend’s front.

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