Marine Weather and Tide Forecast for Marathon, FL

DISCUSSION
Issued at 302 AM EDT Mon Apr 13 2026 The 00z evening sounding at KEY sampled decent shallow moisture up to around 850 mb, capped by a weak temperature inversion. The sounding also detected modest veering with height, and given the continued freshened breezes, isolated to scattered shallow nocturnal showers have been observed across the favored marine zones south of the Island Chain overnight. KBYX reflectivity trends have been downward over the past couple of hours, with only a few isolated showers remaining. Temperatures are generally in the lower 70s at this early Monday morning hour, with mostly clear skies outside of the aforementioned shower activity.

The stagnant synoptic pattern will continue for the remainder of the forecast period for the Florida Keys. Gradient wind associated with high pressure centered east of New England will support continued breezy conditions for the next several days. Aloft, an upper- level ridge, characterized by anomalously high 500 mb geopotential heights, along with the lack of any moisture above the boundary layer, will limit any significant measurable rain amounts as well.

Most deterministic and ensemble numerical weather prediction guidance suggests the ridge may actually strengthen over the next several days. With the gradient that has supported at least isolated showers slowly collapsing late in the week and into the weekend, along with the increased ridging aloft, mainly dry conditions will likely persist at least for the next seven days.

MARINE
Issued at 302 AM EDT Mon Apr 13 2026 A Small Craft Advisory remains in effect for all Florida Keys local waters, as a high pressure system off the coast of New England continues to maintain fresh to strong northeast to east breezes. The freshened breezes will continue through the early portion of this week. Fast- moving light showers cannot be ruled out, especially in the overnight periods. Breezes may briefly lull during the late afternoon and early evening across the Gulf waters due to the heating of South Florida. As the high moves farther eastward and slowly weakens, easterly breezes will modestly slacken for Thursday and Friday.

AVIATION
(06Z TAFS)
Issued at 302 AM EDT Mon Apr 13 2026 VFR conditions will prevail at EYW and MTH through 06z Tuesday morning. Although passing light showers will be possible, mainly in the overnight hours, impacts to the visibilities and ceilings will be minimal. Near-surface winds out of the east will remain gusty, with frequent gusts to 20 to 22 knots expected, mainly in the evening hours.

PRELIMINARY POINT TEMPS/POPS
Key West 82 72 82 73 / 10 10 10 10 Marathon 80 73 81 73 / 10 10 10 10

KEY WATCHES/WARNINGS/ADVISORIES
FL...None.
GM...Small Craft Advisory until 5 PM EDT this afternoon for GMZ031>035-042>044-052>055-072>075.