June is historically the least active month of the 6-month hurricane season.

The storms that form tend to stay on the weaker side – only three Category 3 or stronger hurricanes have ever been recorded in June: Audrey (1957), Alma (1966), and Beryl (2024) – but when tropical storms or the less common hurricane does form in June, they tend to do so closer to the U.S. And typically, it’s rainfall and flooding – not strong winds – that are the hallmarks of these early bloomers.

But it’s during the opening weeks of the season especially that formations happen closer to home in the western Caribbean, Gulf, and off the southeast U.S. Only once in our record books has a tropical cyclone formed east of the islands in the first few weeks of June (Tropical Depression Two in 2003 that didn’t even survive a full 24 hours), which means we generally have less time to prepare when an early season storm threatens.

Two primary triggers are responsible for development in early June: stalled fronts draped over the Gulf or western Atlantic and the Central American Gyre or CAG – a broad area of storminess and spin extending from the eastern Pacific into the Caribbean that can be a breeding ground for tropical systems in shoulder months like June, October and November.

As we mentioned in yesterday’s newsletter, we have a cold front diving into Florida over the next few days that’s expected to stall out across South Florida by late week and into the weekend. But for now models aren’t showing any areas of organized spin along the stalled front, with wind shear remaining prohibitively high into early next week.

MJO makes a go by mid-June

During the early months of the hurricane season, we also look to the progression of the Madden-Julian Oscillation or MJO – a see-saw configuration of upper-level winds that moves around the globe every 30 to 60 days. The MJO has a stormy side and a dry side and it’ll be trending toward the stormy side in the Atlantic by mid-month, according to forecast models.

Areas of rising (blue/cool colors) and sinking (red/warm colors) air straddling the equator (between 15°N and 15°S) by global longitude (x-axis) from early May (top of the chart) through July 17th (bottom of the chart). The time vs. longitude chart is known as a Hovmöller diagram and shows the global progression of the Madden-Julian Oscillation or MJO and its Kelvin Wave components. Rising air that can favor development (part of the MJO) will be moving into Atlantic from the eastern Pacific over the next few weeks. We’ll watch for development potential around Central America and into the southern Gulf for the middle part of the month, but for now long-range models don’t show significant development odds on the Atlantic side. Credit: ECMWF.

This could promote more organized storminess in the Caribbean or Gulf starting late next week, but right now the long-range models are wholly unimpressed. We’ve seen some hints of mischief in the southern and western Gulf a few weeks out in intermittent model runs, but the signal’s been weak and inconsistent. It’s also worth noting that with the developing El Niño in the eastern Pacific – something we detailed in yesterday’s newsletter – the MJO will likely have less influence this season than it would otherwise.

We’ll keep an eye on the trends, but for now, things will stay quiet in the Atlantic, as they often do to start the season.

Where could we see tropical development for the first half of June?

Forecast models are mostly mum for now, but we’ll be watching 2 features in the weeks ahead

About The Author

Michael Lowry