MIAMI (CBSMiami/AP) – South Florida’s wet season is tardy this year, leaving double-digit rain deficits, a drought-stricken river of grass and increasing angst over wildfires.

But an atmosphere constipated by high pressure is finally on the move, promising showers this weekend that water management district meteorologists believe may mark a shift to the reliable afternoon rains and miasmic humidity that define summer.

READ MORE: Shark Bites Florida Man Swimming Near Fishing Line

While the National Weather Service in Miami has a hard start date of May 15 for the onset of rainy season – a reminder that dangerous thunderstorms loom – the timeline can be fickle. The NWS office in Melbourne declares the beginning of rainy season in hindsight, after reviewing weather patterns, but does have median start dates of May 23 for Stuart, May 25 for Fort Pierce and May 26 for Vero Beach.

“It’s likely going to be this weekend,” said Todd Kimberlain, a senior meteorologist with the South Florida Water Management District, about the kickoff of rainy season. “From what I can tell, this will be one of the top 10 driest dry seasons for the district since 1932.”

In West Palm Beach, as measured at Palm Beach International Airport, just 7.4 inches of rain has fallen since Jan. 1 – a whopping deficit of 10.2 inches, according to the Southeast Regional Climate Center.

This month less than an inch of rain fell in West Palm Beach when the normal amount is 4.9 inches.

Similarly, Fort Pierce is down 6.2 inches for the year, Fort Lauderdale is at a 7.2-inch deficit and Key West is down 3.7 inches.

“I’ve bumped my sprinkler times up from 12 minutes per zone to 15 minutes, but I am still getting a bit of drying and hot spots,” said Carl May, who manages property on Palm Beach.

May said hand watering dry areas in the morning or late afternoon, and using a wetting agent that makes it easier for water to penetrate crusty soil should help until the rains begin.

“All of us are awaiting some good downpours,” he said.

HOW A DROUGHT ESCALATES BLUE-GREEN ALGAE CONCERNS

That includes the Loxahatchee River, which relies during the dry season on water from Grassy Waters Preserve – the main water supply for West Palm Beach and Palm Beach.

The City of West Palm Beach stopped taking Lake Okeechobee water to buoy Grassy Waters in late April because of concerns over blue-green algae. Reserve eastern well fields were tapped to keep water flowing to homes and businesses, but this week West Palm Beach said it could no longer send water to the Loxahatchee River.

Freshwater is needed in the river to fight a constant bombardment of saltwater from the Jupiter Inlet, which damages brackish water ecosystems.

Poonam Kalkat, the city’s director of public utilities, said the city is revaluating the water quality in the canal from Lake Okeechobee that feeds Grassy Waters. If Grassy Waters can be restored, it could restart its supply to the river.

“I’m not calling for any water restrictions, but people should not be over irrigating,” Kalkat said.

City of Stuart officials asked residents Wednesday in a social media post to limit outdoor water use because a lack of rainfall is taxing its water treatment plant.

LATEST DROUGHT MONITOR REPORT SHOWS DRY CONDITIONS

READ MORE: Man Struck, Killed On I-95 Near Broward Boulevard

The U.S. Drought Monitor report released Thursday shows all counties south of Lake Okeechobee either as “abnormally dry” or in “moderate drought”. Palm Beach County through Martin County and the southern half of St. Lucie County have abnormally dry conditions – the lowest severity level on the drought monitor scale.

Collier, mainland Monroe and western Broward counties were in moderate drought, including parts of Everglades National Park and Big Cypress National Preserve.

“If we don’t see any quality rain soon, that drought discussion will have to take place again,” said Miami-based NWS meteorologist Robert Garcia. “The surface is parched and even groundwater is starting to get lower.”

The 2021 dry season follows a prolonged 2020 rainy season that was exacerbated by tropical cyclone activity, including Eta, which was a tropical storm when it soaked South Florida in early November.

That set up an ideal situation for wading birds who need rains to spread prey out on the landscape, and then dry weather to condense the fish into pools where they are easy to catch.

It was not great for Lake Okeechobee, however, which swelled to more than 15 feet above sea level before dropping rapidly in recent weeks to its position Thursday at 12.9 feet. If the lake gets too high, the Army Corps must release water, often tainted with harmful algae, to the St. Lucie Estuary, and increase water releases to the Caloosahatchee River.

Kimberlain said the lack of rain coupled with unusually dry air have increased evaporation on the lake.

“Its been in a steep decline, but it’s what you would expect this time of year with no rainfall,” he said.

Akin Owosina, hydrology bureau chief for the South Florida Water Management District, said earlier this month that he would prefer the lake to be 12.5 feet above sea level before showers begin in earnest.

Cool fronts with air originating in Canada helped cut down on humidity levels this month, with dew points more typical of what is experienced in March and February. Even with strong easterly winds bringing in moisture off the Atlantic, there wasn’t enough in the water vapor in the air to turn into rain.

LOW WIND SPEEDS HELPING LIMIT FLORIDA WILDFIRES

The low dew points have piqued concern over wildfires, but wind speeds haven’t met the threshold for an official alert to be issued by the NWS in Miami. Much of western Florida from the Panhandle through the Keys had a very high risk of fire danger Thursday. Palm Beach County and the Treasure Coast had a moderate-to-high level.

A 585-acre wildfire burned Monday in Palm Beach Gardens, but was extinguished by Tuesday night. An Indian River wildfire, dubbed the Tree Frog fire, burned 1,100 acres this month before being contained.

Lightning strikes can start wildfires, which is a concern this weekend into early next week as thunderstorm chances increase.

“Most years, the wet season comes on quickly and very strong,” Kimberlain said. “On Saturday, we’ll see a pretty big increase in moisture.”

In West Palm Beach, rain chances are 20% Saturday, 30% Sunday, and increase to 50% on Memorial Day. Thunderstorms are possible throughout the weekend with the NWS warning of rip currents along Atlantic beaches.

MORE NEWS: Tropical Storm Warning Extended For Northern Gulf Coast Ahead Of Potential Tropical Cyclone Three

(© Copyright 2021 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)