When The First Hurricane Of The Atlantic Season Typically Happens

The Atlantic hurricane season officially begins June 1, but it usually takes a month or more before the season's first hurricane develops.

For seven years in a row through 2021, hurricane season started early, with at least one named storm before the official June 1 kickoff of the season.

But how long does it usually take before the first hurricane develops?

To answer that, we looked at data from the mid-1960s – when full satellite coverage of the Atlantic Basin began – through 2023 to see how variable the date of the season's first hurricane has been. We also examined where those first hurricanes formed and whether early or late first hurricanes told us anything useful about the season as a whole.

It usually happens in July or August. In 41 of the 58 years since 1966, the first Atlantic hurricane of the season formed in either July or August.

This makes sense.

Very early in the season, wind shear that can disrupt or rip apart tropical cyclones is still at least modest. Areas of sinking, dust-laden air from the Sahara Desert push westward across the Atlantic, suppressing thunderstorms needed for tropical development.

Beginning in July, tropical waves – the disturbances often serving as the seeds of tropical storms and hurricanes – become more numerous migrating westward off the African coast. Wind shear diminishes toward its seasonal low, and ocean temperatures warm in the summer heat. These are all favorable factors that combine to support not just tropical storms, but also hurricanes.

But there's variability. Now let's look closer at the actual dates of the season's first hurricane over the last 58 years, plotted in the graph below.

They're plotted as Julian days – where Jan. 1 would be Julian day 1, Feb. 1 Julian day 32 and so on. We did this in order to calculate the average day you'd expect the first hurricane of the season to have formed by, which was July 26.

But as you can see, this date can vary year to year.

In 1970, Alma briefly became a hurricane on May 20 between Jamaica and Honduras before it weakened to a tropical depression 36 hours later in the western Caribbean Sea.

In 2016, Hurricane Alex made a freakish mid-January appearance south of the Azores in the eastern Atlantic Ocean.

We've also had very long waits for the first hurricane, including several times this century.

Does the timing of the first hurricane portend an active season? Since 1966, we found 14 seasons in which the first hurricane arrived at least three weeks earlier than the July 26 average, 21 seasons in which it arrived within three weeks of the average date, and another 23 seasons in which it formed at least three weeks later than average.

As you might expect, "early first hurricane" seasons had about two to three more storms and about two more hurricanes than "late first hurricane" seasons.

However, the years with a near-average arrival of the first hurricane ended up with the most storms and hurricanes of all.

Since the majority of a season's activity occurs during its late August through September peak, whether a storm manages to reach 75 mph winds in June or early July shouldn't matter for the overall season. One caveat to this, though, is the tendency for an early hurricane in the so-called main development region between the Lesser Antilles and west Africa to foreshadow an active season.

However, note there were about three fewer storms and two to three fewer hurricanes in seasons with a late-arriving first hurricane compared to average.

That also make sense.

If it takes until late August or September to finally generate a hurricane, there may be large-scale conditions – such as persistent wind shear or sinking, dry air – over the Atlantic Basin that are more hostile for tropical development.

Here's where the first hurricanes get started. We also plotted on the map below the locations of each of the season's first hurricanes since 1966. As you can see, there's a lot of spray in these points.

In general, the earlier-season hurricanes tend to form in the western Atlantic, Gulf of Mexico or Caribbean Sea, which matches the areas that are typically favorable for development in June or early July.

First hurricanes forming later in the season can form over a larger part of the Atlantic Basin.

Prepare now. Perhaps the main takeaway from the map above is how many become the season's first hurricane relatively close to the U.S., particularly in the Gulf of Mexico.

While not all of these make landfall, particularly those off the East Coast, it's a reminder that the time to prepare for hurricane season is now.

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. His lifelong love of meteorology began with a close encounter with a tornado as a child in Wisconsin. He completed a Bachelor's degree in physics at the University of Wisconsin-Madison, then a Master's degree working with dual-polarization radar and lightning data at Colorado State University. Extreme and bizarre weather are his favorite topics. Reach out to him on X (formerly Twitter), Threads, Facebook and Bluesky.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives.