Marine Weather and Tide Forecast for Key Colony Beach, FL

DISCUSSION
Issued at 1130 AM EDT Mon May 18 2026 This morning has looked very similar to yesterday across the Florida Keys! Temperatures are currently in the mid to upper 80s with dew points in the upper 70s. This gives us heat index values in the mid to upper 90s, which is within a degree or two compared to this time yesterday.

Our KBYX radar has been busy detecting pockets of shower activity across the area. The heaviest showers have remained to the south and southwest of the Lower Keys, so we guess the marine life may be enjoying it. It is almost a little surprising that there isn't more shower activity on radar. The 12Z KKEY sounding calculated a PWAT value of 1.84", which is very close to the 90th percentile value of 1.86". The profile seems to be moist enough with only a couple of slots of dry air in the upper levels, but there is a small, shallow cap noted at 935mb. Our initial guess as to why shower coverage may be lacking is that there isn't any notable synoptic scale feature to provide robust lift. The low level flow also appears to be fairly uniform. Low level wind speeds are roughly 15 to 20 knots, so any outflows that have been produced by collapsing showers haven't had the opportunity to collide with other outflows. Radar trends suggest that a drastic increase in shower coverage may not occur during the daytime hours, but hi res guidance is hinting that the best chance for this will be later this evening. Either way, the inherited 40 percent PoPs seem reasonable considering these factors. No changes or updates are needed with this morning update.

PREV DISCUSSION
Issued at 440 AM EDT Mon May 18 2026

Additional moisture to our east should pivot in throughout the rest of today. This combined with an already accelerated flow, should help to smash any mesoscale boundaries out there, allowing for showers to increase in coverage again. This enhanced moisture pool will linger through tonight and gradually begin scouring out starting Tuesday. This will not be a fast process and rain chances will be slow to diminish through the week. Meanwhile, a high pressure near Bermuda will flatten over the next several days, weakening the pressure gradient through the end of the week. This will lead to generally a slackening of winds, though there will still be some peaks in the evenings at times.

By the end of the week we may have an easterly undulation move through the Bahamas and along the east coast of Florida, injecting more moisture back across the area, and subsequently rain chances.
It's too far out to get our hopes up at this time.

MARINE
Issued at 1130 AM EDT Mon May 18 2026 Small Craft Should Exercise Caution across all Florida Keys local waters due to east to southeast winds of 15 to 20 knots. From synopsis, surface high pressure centered near Bermuda will continue to promote moderate to fresh east to southeast breezes through the next couple of days. Breezes then undergo a very slow slackening process with peaks expected during the evenings and lulls during the day. Rain and thunder chances will remain above normal through much of the week.

AVIATION
(15Z TAFS)
Issued at 1036 AM EDT Mon May 18 2026 VFR conditions will prevail at both island terminals with FEW to SCT skies based between FL020 and 030. Short lived pop up showers will continue to traverse the area, and may clip either air field at virtually any point in the TAF period. Opting to keep the beginning of the package free of showers, and introducing VCSH from 20Z onward.

PRELIMINARY POINT TEMPS/POPS
Key West 91 80 91 80 / 40 40 40 30 Marathon 87 79 86 80 / 40 40 40 30

KEY WATCHES/WARNINGS/ADVISORIES
FL...None.
GM...None.