This summer’s forecast: hotter than normal. Will there be rain relief? What to expect.

Another hotter-than-normal summer is on its way. But it’ll take some time for South Florida to settle into a pattern of rainy days.

The annual National Weather Service wet season forecast for the region is calling for a relatively dry start to the season, which will grow wetter as summer progresses. Experts also say this summer and early fall will be as much as 1.5 degrees F hotter than normal, and likely quite humid.

Last summer’s heat was record-breaking, said Robert Molleda, head meteorologist at the NWS office in Miami. “It was the hottest on record. We’re not forecasting a repeat of last year, but we’re forecasting above-normal temperatures,” he said.

South Florida’s five-month wet season accounts for 60% to 70% of the region’s annual rainfall.

Thunderstorms often rise over the ocean in the morning, and as the day heats up, form over inland areas in the afternoon. Storms are a daily or near daily occurrence.

Molleda divided the wet season into three phases. The first six weeks, up to the first week of July, are usually the stormiest of the year, with a greater likelihood of severe thunderstorms, hail, tornadoes and flooding.

But the NWS models for this year show an equal chance of above or below normal rainfall in May and June.

The hottest and driest phase is usually from July into August, as the Bermuda High and sometimes dry Saharan dust can impact the region.

This year, though, the NWS is calling for above-normal rainfall in the second half of the wet season.

The models are more definitive about how hot it will be. “We have more confidence on temperature,” Molleda said. “Temperatures could average 1.5 degrees above normal.”

NWS models are forecasting a 90% or greater chance of higher-than-normal temperature for the entire season.

An additional heat factor is the high water temperatures off Florida’s coast.

“That can contribute to higher nighttime temperatures, and also result in higher moisture levels, which translates into high heat index levels,” Molleda said. In other words, hot and highly humid.

The heat is part of a larger trend. Based on records starting in the 1890s, summers started getting hotter in South Florida in the 1990s, and have continued to do so.

El Niño and La Niña

As of early May, there was still a bit of an El Niño in effect, but Molleda said that would fade, and that there was a 60% chance of La Niña emerging some time in June, July or August.

Those odds kicked up to 80% in August, September and October.

La Niñas can enhance hurricane formation by creating calm conditions and high moisture over the Atlantic. The result is hot water, and no wind to topple cyclone formation.

Based on current water temperatures in the eastern Pacific, most models indicate a weak to moderate La Niña.

Though La Niña can lead to more hurricane formation, Molleda’s data showed that that does not necessarily translate to more landfalls.

Lake Okeechobee

Lake Okeechobee water levels are a concern at this time of year, as the wet season and tropical storms and hurricanes can rapidly raise the waters to dangerous heights.

The South Florida Water Management District and Army Corps of Engineers typically lower the lake in anticipation of the wet season.

In the past, that has sometimes resulted in massive and destructive discharges of fresh water, often tainted with blue green algae, to economically valuable saltwater estuaries near Stuart on the east coast and Fort Myers Beach and Sanibel Island on the west coast.

Matahel Ansar, of the SFWMD, said that the lake is a tad high for this time of year, at 14.06 feet, but that the entire system of canals and stormwater treatment areas has good water storage levels, despite the wet winter.

“The fact that we had a dry April really helped us out,” Ansar said.

Major Cory Bell, of the Army Corps of Engineers, said the Corps is aiming to bring Lake Okeechobee levels down another foot, even as the wet season begins, and they have no plans for major releases of lake water into the fragile estuaries to the east and west.

Ansar added that the district is looking to move water south into the Everglades, which would also help alleviate harmful discharges to those estuaries.