A mariner's poem clocks hurricane season by the likelihood of danger.

June too soon, goes the rhyme, according to a report by the National Hurricane Center.

July stand by.

August look out you must.

September remember.

October all over.

It has been a relatively quiet Atlantic hurricane season so far. But experts are warning residents in high-risk areas — and that includes all of Florida — to remain vigilant and prepared.

For today marks only the midpoint, and also the start of what historically has been the most active month of the season.

On cue, forecasters are watching two tropical systems, one rolling west from Africa, the other in the Caribbean. If you charted the likelihood of a tropical storm or hurricane spinning in the Atlantic, if would look like a wave that crests Sept. 10.

Residents here may remember: That's the same date Hurricane Irma made landfall last year in Florida, not once, but twice, before turning the lights out on much of the state.

A MATTER OF MILES: How the slightest shift kept Hurricane Irma from turning into an even worse disaster

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Until mid-August, this hurricane season actually delivered above-average activity. But the storms didn't pose much of a threat.

Two hurricanes spun to life early in the season, in July. Beryl, which originated in the tropical Atlantic on July 5, was a short-lived Category 1 hurricane that hit Hispaniola as a tropical wave. And Chris formed off the South Carolina coast on July 6, strengthened to a Category 2 hurricane and traveled toward Newfoundland before petering out.

Subtropical Storm Alberto, which threatened Memorial Day Weekend, and two August tropical storms — Debby and Ernesto — which didn't affect land, round out this season's five named storms.

But about two weeks ago, the season started to fall behind. The month of August didn't produce a single hurricane.

For that, thank the cooler-than-normal ocean temperatures in the tropical Atlantic — hurricanes feed off warm water. Also, the Pacific Ocean is trending toward El Niño conditions, the phenomenon of warmer-than-average water that produces high-level winds across the tropical Atlantic. Those winds deter hurricane formation. A full-blown El Niño might develop by the end of the season.

Basically, said Phil Klotzbach, a hurricane researcher at Colorado State University's Department of Atmospheric Science, such a vast majority of hurricane activity occurs during the peak weeks of the season that any activity early on makes for an above-average year, but each week without a storm during the peak means the season falls behind.

"The climatological curve really ramps up this time of year," he said.

IMAGES: What Hurricane Irma did to Florida

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The high-level winds and cooler water temperatures don't prevent all storms, though. Sometimes, they form anyway.

Scientists are currently tracking a tropical depression off the coast of Africa that they say likely will develop into a storm and later a hurricane. It would be called Florence, the sixth named storm.

They're also watching a disturbance in the Caribbean. Its chances of development in the next five days remain low, though, according to the National Hurricane Center.

It could be just the beginning, thanks, in part, to something called the Madden-Julian Oscillation. The oscillation is a disturbance of clouds, rainfall and pressure that circumnavigates the Earth every 30 to 60 days, according to the National Oceanic and Atmospheric Administration. Klotzbach said it is predicted to strengthen over Africa within a week or two, causing unsettled air in the heart of the Atlantic's hurricane development zone. Its presence during the peak of the season could yet produce a burst of activity.

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GET PREPARED: Tampa Bay Times 2018 Hurricane Guide

For those who didn't get a hurricane plan together before the season started, the midpoint presents another chance, said Kevin Guthrie, Pasco County's assistant county administrator for public safety and its de facto emergency services director.

He said residents should get knowledgeable now about their home and supplies, not wait for a storm to bear down. Some key questions, Guthrie said: Is my house in a flood zone? Can it withstand the wind? Does it need work done? Do I have enough canned food, water and flashlights?

The year 1996 is key, Guthrie said. Homes constructed after that year were built to meet stronger codes, a result of 1992's Hurricane Andrew, which decimated southeastern Florida. Older homes were built to a lower standard.

Once storm warnings are announced, it can be too late to get a plan together, said National Hurricane Center spokesman Dennis Feltgen.

"You're going to be one of those hundreds of people standing in line for supplies in those big box stores," Feltgen said.

When it comes to evacuating, Guthrie said, it's important to heed the warnings of authorities. And those who must evacuate should do so tens of miles, he said, not hundreds. Going too far can clog the roads unnecessarily.

"You don't need to go all the way to Atlanta, Ga.," he said.

As for shelters, Gulthrie said to think of them as a life raft, not a cruise. They are a life-saving measure, and should be a last resort. Staying with friends or relatives is much more comfortable.

When it comes to planning, Feltgen said, it doesn't matter what forecasters say about a particular season's activity level. There's no way to predict ahead of time who might get hit by a storm, and bad storms can happen in otherwise quiet years, as Andrew did. Readiness is key.

"If you do get hit, it doesn't matter who said what about activity," Feltgen said. "You got hit, you had a really bad year."

Contact Josh Solomon at (813) 909-4613 or jsolomon@tampabay.com. Follow @ByJoshSolomon.