The 2016 hurricane season just shifted from sleepy to fierce.

Tropical Storm Hermine strengthened into a hurricane Thursday, just in time to strike the coast of Florida — the first hurricane to hit that state in nearly 11 years.

As that storm moved up the Atlantic coast, in the Pacific two other storms threatened Hawaii. And there are probably more to come before the season concludes at the end of November.

This is, in other words, the height of the season, that time of year when conditions are the most favorable for making cyclones — and for making coastal residents nervous. It is also the moment that puts on display much of what we know, and still do not know, about hurricanes, and what to expect as climate change progresses.

Much of this, so far, is normal. This season is shaping up within the forecasts from the National Oceanic and Atmospheric Administration, which predicted in May that in the Atlantic there was a 70 percent likelihood of as many as 16 named storms. As many as eight of them, the agency said, could become hurricanes (that is to say, with winds of 74 mph or more), and as many as four could be major, Category 3 hurricanes with winds of 111 mph or higher.

So things are on track in the Atlantic. In the Pacific, however, there have been some unusually strong storms and busy seasons in recent years.

All of this activity comes after what some meteorologists and news reports have called a long hurricane drought, citing a nearly 10-year run without major hurricanes making landfall on the mainland. While that is literally true by the definitions used by climate scientists, any discussion of a hurricane drought can seem insulting to people in the Northeast and along the Texas Gulf Coast, where the so-called Superstorm Sandy and Hurricane Ike caused billions of dollars in damage.

The efforts to detect a lull involve arbitrary line-drawing exercises, Robert E. Hart of Florida State University wrote in a recent paper with Daniel R. Chavas of Princeton and Mark P. Guishard of the Bermuda Institute of Ocean Sciences. A Category 3 hurricane at landfall is considered a major storm; Hurricane Ike, for all its destructiveness, missed that mark, and Sandy was not considered a hurricane by the time it struck, but instead an extratropical storm.

Regardless of whether the definitions of hurricane drought should be changed, Hart said long periods without storms can foster dangerous complacency. “Memory fades about the prior events, and more people have never experienced one than before,” he said.

The last major hurricane to hit Hawaii was Iniki in September 1992, which hit Kauai hardest, killed six people and damaged or destroyed more than 14,300 structures. Iniki caused $2.8 billion in damage on Kauai and the Waianae Coast.

When it comes to hurricanes and climate change, scientists are still trying to figure out what warming is doing now and will do later.

“It’s a really tough problem,” said Gabriel A. Vecchi, a climate researcher at the geophysical fluid dynamics laboratory of the NOAA in Princeton.

The issue might appear to be simple: Warmer oceans provide more energy for storms, so storms should get more numerous and mighty. But other factors have complicated the picture, he said, including atmospheric changes that can affect wind shear, a factor that keeps cyclones from forming.

Kerry A. Emanuel, a climate scientist at the Massachusetts Institute of Technology, said the evidence suggested climate change would cause the strongest storms to grow even stronger and to be more frequent. Unresolved questions surround the effect of warming on the weaker storms, but even those will dump more rain, leading over time to increased damage from flooding.

In the Pacific, and especially near Hawaii, there is some evidence that the tendency toward more storms and stronger storms is underway, Vecchi said. Additionally, because warmer waters now extend farther north, tropical storms now routinely pass north of the islands, where in the past they stuck to the south.

Hiroyuki Murakami, an associate research scholar at the Princeton laboratory, said that the unusually active hurricane seasons for Hawaii were being caused mostly by subtropical warming that is part of the ocean’s natural variability, but that human-caused climate change was also having an effect. His recent research, he said, suggests that active hurricane seasons in the Pacific will grow more frequent under the influence of warming, though natural variability will still play a role in the record for any individual year.

Finding the telltale “signal” of climate change in events is challenging, Emanuel said, because there are relatively few storms from which to draw data.