Marine Weather and Tide Forecast for Big Pine Key, FL

DISCUSSION
Issued at 410 AM EDT Sat Jun 13 2026 One need only step outside to get an idea for weather this weekend across the Florida Keys. Breezes slackened to light to gentle east southeasterlies along the reef yesterday. Mostly sunny skies indicate few limitations to daytime heating, and dew points across the Keys this morning are in the lower to mid teens. While it may be tempting to state that showers are not a concern, KBYX radar scans detected isolated thunderstorms north of the Lower Keys this morning along an extremely weak outflow boundary. The moisture and instability is present but we lack a forcing mechanism. However, the atmosphere may provide one today. Near surface winds are easterly to southeasterly, which suggests cloud lines may be able to form west of the Lower Keys. Any outflow boundaries coming off of Cuba or southern Florida could initiate showers.
The complicating factor to this scenario is a decaying Saharan Air Layer. Both yesterday's soundings sampled a dry layer from 900 mb to 650 mb. Based on the trend observed by the radar, the forecast will carry 20% PoPs today. Aside from a short-lived thunderstorm and potential waterspouts, the main issue today, and what will be the problem for the upcoming heat, will be heat.

The synoptic pattern shifted little from yesterday's analysis. A tropical disturbance is over the Bay of Campeche and is on track to move inland onto Eastern Mexico. High pressure over the Atlantic shifted further east. A very deep mid latitude trough continues to deepen over the Canadian provinces of Nunavut and Ontario. These features are primed to keep the Atlantic high weak and maintain broad lower pressure over the eastern United States through the start of next week. Across the Florida Keys, this means light to gentle breezes and sinking air aloft. Plus, deterministic models are hinting at a more pronounced SAL approaching the Keys next week. Unfortunately, these features are very unlikely to do anything to lower the surface dew point, and model guidance resolves mid 70s dew points throughout the week. The takeaway is that there is high confidence temperatures and heat indices are going to increase next week. Lighter breezes also mean the air may become more stagnant, particularly around the larger islands. Remember to stay hydrated, take breaks, and prepare to deal with the heat.

MARINE
Issued at 410 AM EDT Sat Jun 13 2026 No watches, warnings, or advisories are in effect for the Florida Keys coastal waters. From synopsis, light to gentle east to southeasterly breezes will persist across the Florida Keys today.
The combination of a well developed mid latitude trough over the eastern United States and a weak disturbance over the Bay of Campeche weakened the ridge over the Caribbean Sea. Breezes are on track to veer southeast to south late in the weekend and early next week. Dry conditions are expected to persist throughout the weekend.

AVIATION
(06Z TAFS)
Issued at 410 AM EDT Sat Jun 13 2026 VFR conditions will prevail at EYW and MTH for the upcoming TAF period. Patches of MVFR CIGs may be able to form near the terminals. Showers cannot be ruled out, but there is not sufficient confidence in the timing or location of VCSH to include in the TAFs.

PRELIMINARY POINT TEMPS/POPS
Key West 89 81 89 81 / 10 10 10 10 Marathon 89 81 90 81 / 10 10 10 10

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