How Hurricanes Form and Why So Many Are Active Right Now

A hurricane is a powerful rotating storm that forms over warm ocean water when heat and moisture organize into a spinning system with sustained winds of 74 mph or higher. The name “hurricane” specifically applies to storms that form in the Atlantic and the eastern or central Pacific; the same kind of storm goes by other names elsewhere. Late September 2026 has turned into an unusually crowded stretch, with several separate systems spinning across the Pacific and Atlantic at the same time.

How does a hurricane actually form?

A hurricane forms when warm, moist ocean air rises, cools, and condenses, releasing heat that pulls in more air below it and kicks off a self-sustaining cycle of rotation. A handful of ingredients generally need to line up at once: ocean water warm enough — roughly 80°F (26.5°C) or higher — across enough depth that the storm doesn’t churn up cooler water and cut off its own fuel; a moist, unstable atmosphere that lets thunderstorms build tall; low wind shear, since strong shear tears a young storm apart before it can organize; and enough distance from the equator for the Coriolis effect, Earth’s own rotational spin, to twist rising air into an organized system rather than a disorganized cluster of thunderstorms. Most storms start as a “tropical wave,” a loose band of showers, and only a small fraction ever develop the closed, spinning circulation that earns a name.

What’s the difference between a tropical depression, a tropical storm, and a hurricane?

The difference comes down to sustained wind speed at the storm’s center. A tropical depression has winds of 38 mph or less. Once winds reach 39 mph, the system is upgraded to a tropical storm and given the next name off the season’s pre-set list. Once sustained winds reach 74 mph, it officially becomes a hurricane. Each stage also tends to come with tighter organization — a hurricane typically develops a clear eye, a calm column of sinking air at its exact center, ringed by the eyewall: the band of the storm’s most intense thunderstorms and its strongest winds.

What do the hurricane categories actually mean?

Once a storm becomes a hurricane, its category on the Saffir-Simpson Hurricane Wind Scale is based purely on sustained wind speed, from Category 1 up to Category 5. It’s a wind-only measure — it doesn’t account for storm surge, rainfall flooding, or tornadoes spun off by the storm, which are frequently the deadliest part of a landfalling hurricane.

Categories 3 and above are classified as “major hurricanes.” The National Hurricane Center’s own damage descriptions for that range include widespread roof and structural failure, with power and water outages that can stretch from weeks into months.

Why are so many hurricanes active right now?

As of Sunday morning, 27 September 2026, the National Hurricane Center was tracking several separate tropical systems at once across the Pacific and Atlantic — an unusually busy snapshot, though not an unheard-of one this late in September. Late September sits close to the historical peak of both the Atlantic season (which peaks around 10 September) and the Eastern Pacific season (which peaks in late August), so overlapping storms are more common in this window than at almost any other point in the year.

As of Saturday evening, the National Hurricane Center was urging that preparations across Baja California Sur “be rushed to completion” ahead of Hurricane Polo. Hurricane Nolo was bringing gusty winds, heavy rain, and large waves to the Hawaiian Islands, and Odalys was weakening over open water. This is a live, moving picture: by the time you’re reading this, some or all of these systems will have made landfall, weakened further, or dissipated, so treat the table above as a snapshot rather than current conditions.

Is 2026 shaping up to be a busy hurricane season overall?

Not necessarily — a cluster of simultaneous storms in late September doesn’t mean the whole season is running hot. Earlier in the year, NOAA’s seasonal outlook for the Atlantic basin called for a below-normal season overall: 7 to 13 named storms, 2 to 6 hurricanes, and 0 to 2 major hurricanes across the full June-through-November window. A busy stretch around the historical peak is consistent with a season that still finishes at or below average, since activity in any one basin is never spread evenly across six months.

Hurricane, typhoon, or cyclone — what’s the difference?

They’re the same type of storm; only the name changes depending on where in the world it forms. In the Atlantic and the eastern or central North Pacific, it’s a hurricane. The identical storm in the western North Pacific is called a typhoon. In the South Pacific and the Indian Ocean, it’s simply a tropical cyclone. The physics — warm water, rising moisture, low shear, organized rotation — is the same everywhere; only the label changes at the map’s edges.

When does hurricane season start and end?

The Atlantic hurricane season runs from 1 June through 30 November, while the Eastern Pacific season runs slightly longer, from 15 May through 30 November. The Atlantic peaks around 10 September; the Eastern Pacific peaks in late August but stays active over a longer stretch of the calendar. The Central Pacific, where Hurricane Nolo was spinning as of this writing, follows roughly the same broad window.

Bottom line

A hurricane is really just a feedback loop — warm water, rising moist air, and low wind shear — that occasionally lines up in several ocean basins within days of each other, which is exactly what made late September 2026 feel so crowded. For a look at what happens when that loop doesn’t quite come together, our recap of Tropical Storm Dolly walks through a 2026 system that fell apart in under 48 hours instead of strengthening. The same habit applies every hurricane season regardless of how many storms are on the map at once: check the National Hurricane Center’s own advisories for anything near you, since these systems can change within hours.