textproduct: Key West

KEY MESSAGES

- Rain and thunder chances will remain elevated during the overnight hours, and will diminish before sunrise.

- Heat will be the primary weather concern over the next seven days. Heat indices may creep towards 110 beginning this weekend.

- A Saharan Air Layer will begin spreading across the Keys over the weekend into next week, keeping rain and thunder chances slight at best.

DISCUSSION

Issued at 945 PM EDT Fri Jul 10 2026 This may be an understatement, but weather has been a little busy throughout this evening shift. Earlier this afternoon, multiple outflow boundaries from Cuban convection provided the surface lift to initiate convection, and a shortwave trough in the mid to upper levels noted on GOES-19 Water Vapor imagery provided the support needed to maintain this activity. We don't have a reasonable estimate as to how many lightning strikes have been produced since all of this started, but it wouldn't surprise us if there have been thousands of strikes over the course of today. Not only have these thunderstorms been particularly electric, they have also been hefty wind producers. Some of the strongest gusts that were recorded tonight were at Marathon International Airport with a gust of 48 mph, or 42 knots, and at the Sand Key Light C-MAN Station with a gust of 46 mph, or 40 knots. We are sure there were more gusts similar to this, but there were no observations sites to record them. Unfortunately, conditions were unfavorable for a radiosonde release this evening, so we don't have a sounding that offers real time data in the vertical profile. Based on the radar loop, it's a safe bet that the profile is saturated, and just icy enough to support ongoing frequent lightning.

The good news is that all of this rain has helped to cool things off just a little bit. While temperatures during the afternoon were anywhere from the upper 80s to the lower 90s, with heat index values in the lower to mid 100s, our current automated sites along the island chain are reporting temperatures anywhere from the upper 70s to mid 80s. Our warmest location is still the northern portion of Key Largo where the current temperature is 86F, but showers are still approaching that part of the island chain. The upper level trough will continue to gradually lift out of the area during the overnight hours while the current mess of showers and thunderstorms continues to work over the environment. This will allow for conditions to slowly calm down, and things should look entirely different by tomorrow afternoon.

THe inherited forecast has a chance of showers and thunderstorms, roughly 30% to 40%. This may seem a little low at face value considering the amount of activity ongoing at this time, but when looking at the entire overnight period, it seems like a reasonable value. No changes are being made to the current package considering that the bulk of the PoPs are ongoing now, and we will calm down eventually overnight.

MARINE

Issued at 945 PM EDT Fri Jul 10 2026 Widespread showers and strong, embedded thunderstorms will continue to traverse the local waters throughout the overnight hours. Winds will be stronger and seas will be rougher and higher in and near showers and thunderstorms. This activity will taper off during the overnight hours. By Saturday afternoon, gentle to modestly moderate east to southeast breezes will prevail, and seas will gradually subside over the weekend. Another Saharan Air Layer will help to keep rain and thunderstorm chances low, less than 10 percent, through the extended forecast.

AVIATION

(00Z TAFS) Issued at 945 PM EDT Fri Jul 10 2026 Showers and thunderstorms will continue to track across the area during the early part of the TAF period, and occasional MVFR to IFR conditions, mainly due to lowered CIGs. Very isolated pockets stronger thunderstorms may bring LIFR VIS to either terminal, but this likelihood diminishes greatly after 05Z. Most of the efficient showers and thunderstorms should taper off well before sunrise, and drier conditions will settle in for the day with east to southeast surface winds near 10 knots.

PRELIMINARY POINT TEMPS/POPS

Key West 83 93 83 92 / 40 10 10 0 Marathon 83 90 84 90 / 40 10 10 0

KEY WATCHES/WARNINGS/ADVISORIES

FL...None. GM...None.