textproduct: Key West

KEY MESSAGES

- Measurable rain chances will remain low through the weekend, only up to 10% for each forecast period.

- Conditions will remain seasonably warm and muggy, but we may see heat index values above 105F, particularly along the Upper Keys, through Friday.

DISCUSSION

Issued at 405 AM EDT Fri Jun 19 2026

A little bit more activity on the KBYX radar, but honestly that's not saying much given the current dull regime we have been in. Slightly better moisture is pivoting up in the southeast flow along the western periphery of a broad, weak high pressure. This is manifesting more in the way of cloud cover, but a few isolated showers are attempting to develop this morning. Meanwhile, the southeast flow has kept conditions rather stagnant and we set another warm low temperature record at Key West, while tying at Marathon. Dew points remain locked in the upper 70s and this is creating heat index values in the mid to upper 90s for many island communities.

Despite the slightly better plume of moisture that will move through this morning, only expecting slight chance PoPs (10 percent) for today. Deep layer subsidence remains solidly in place and will continue to inhibit large scale vertical growth of any showers. Meanwhile, a quasi-stationary boundary in conjunction with the remnants of Arthur have weakened and splintered the broad ridge that sits across the Atlantic and well across the Gulf Basin.

This splintering will lead to a weakening pressure field across the Florida Keys and will allow for winds to go light and variable. This combine with dew points holding in the upper 70s and daytime highs in the upper 80s will result in very little relief from the 100+ degree heat index values over the weekend. In addition, moisture will remain meager and precipitation chances will remain at 10 percent or less.

As the high gradually strengthen and fills back in we will see winds become east to southeast and a little bit stronger. This will allow for a better wind direction to pull in moisture across the area. It's too soon to say if this will result in relatively better rain chances next week but a somewhat wetter signal is at least present.

MARINE

Issued at 405 AM EDT Fri Jun 19 2026

Gentle to occasional moderate southeast breezes this morning will slacken during the late morning and afternoon before freshening again this evening. This peak and lull cycle will continue into Saturday and Saturday night. Thereafter, high pressure will weaken and splinter across the Gulf Basin, result in winds becoming light and variable. This will be especially true on Sunday and across the waters along and north of the island chain. Starting Monday, high pressure will begin rebuilding across the region and allow for east to southeast breezes to very gradually freshen.

AVIATION

(06Z TAFS) Issued at 405 AM EDT Fri Jun 19 2026

VFR conditions are expected through the forecast period. There is a very low chance of a shower or thunderstorm passing near the EYW or MTH terminal towards dawn this morning, but confidence is too low to include at this time. Otherwise, southeast winds will remain at 10 knots or less.

PRELIMINARY POINT TEMPS/POPS

Key West 91 84 91 83 / 10 10 10 10 Marathon 88 84 88 83 / 10 10 10 10

KEY WATCHES/WARNINGS/ADVISORIES

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