Marine Weather and Tide Forecast for North Key Largo, FL

SHORT TERM
(Today through Tuesday)
Issued at 127 AM EDT Mon Oct 12 2026

A reprieve from humidity, albeit brief, is indeed finally on the way for South Florida today as a weak frontal boundary continues to slide southward across Central Florida early this morning. For the time being however, 05z mesoanalysis reveals that South Florida remains firmly in a plume of deep atmospheric moisture that has pooled along and south of the boundary. Light winds, clearing skies, and the development of a nocturnal near surface inversion could set the stage for patches of dense fog across inland areas of South Florida early this morning (20-40% HRRR probabilities of 0.5 mile or less visibility primarily confined to the south and west of Lake Okeechobee) before diurnal mixing shortly after sunrise disperses any near surface stratus cloud deck and fog.

As a progressive mid-level trough pushes offshore of the eastern United States this morning, 500mb flow will veer from a southerly component to a westerly component by this afternoon. At the same time, the enhancement of a surface low offshore (right entrance region of a southern stream jet-streak) of the northeastern United States will provide enough forcing for the weak frontal boundary currently located across Central Florida to slide southward across our region during the day today. With all of the best dynamics now well removed from the region, convective activity today is forecast to be much more sparse and shallow in nature. That being said, maximized ascent and residual moisture along the boundary could still set the stage for some isolated to scattered shower activity. Dry air advection aloft will keep any convection vertically capped and shallow in nature, which will limit any threat of convective hazards. HRRR and REFS LPMM guidance depict widespread totals remaining less than a quarter of an inch, which is also in line with guidance from the Weather Prediction Center.
High temperatures today will peak in the upper 80s to low 90s during the afternoon hours as lower dewpoint values gradually push southward into the region.

As the boundary slides south of the region tonight into early Tuesday, a dry continental airmass will make a long-awaited return to South Florida. While this will not be a "cold" or even "cool" front by any metric, the change in the air will certainly be noticeable as we drop from forecasted dewpoints in mid to upper 70s today to dewpoints in the upper 60s to low 70s on Tuesday.
Even more remarkable will be the drop in precipitable water values, deterministic and ensemble guidance continue to suggest a potential of seeing precipitable water values across South Florida below the 10% percentile for this time of year. While rain chances will remain minimal (<10%), overnight mesoscale model guidance (HRRR,RRFS,etc) hint at the potential of isolated shallow convection (sprinkles/light rain) pushing onshore along the east coast on Tuesday afternoon. Even in a rather dry weather regime, breezy northeasterly flow above the warm Gulfstream waters can still produce an isolated coastal sprinkle or two. No significant temperature change is expected behind this front during the daytime hours (forecasted highs still reach the upper 80s to low 90s on Tuesday) but a slight drop in overnight temperatures is forecast with the potential of low temperatures in the mid to upper 60s across inland southwestern Florida on Tuesday morning. After the past week of rinse and repeat humidity and deja vu above average overnight temperatures in South Florida, the brief overnight temperature dip on Tuesday morning may feel "crisp" to some. For this forecaster however, I patiently await a cold front with a real kick.

LONG TERM
(Tuesday night through Sunday)
Issued at 127 AM EDT Mon Oct 12 2026

The advertised reprieve from moisture will be a short lived one as the frontolytic boundary and envelope of associated moisture lift back across the region during the day on Wednesday into Thursday as an expansive area of surface high pressure becomes established across the southeastern United States. Northeasterly surface flow will gradually veer to an easterly direction by Thursday as the axis of surface ridging across the southeastern United States slides eastward into the western Atlantic waters. This will focus the best diurnal rain chances across the western half of the peninsula during the second half of the work week, although overnight and morning activity will still be a possibility along the east coast of South Florida given the breezy easterly flow and continued moisture advection. Mid-level ridging briefly established across the southeastern United States during the early to mid portion of the work week will quickly flatten by Thursday as the next lobe of troughing slides eastward across the northern United States. As the positively tilted trough amplifies and digs across the eastern United States, a strengthening surface low will strengthen and push east-northeastward in tandem. Model guidance remains in agreement that a surface frontal boundary attached to the aforementioned surface low will push southwards across the eastern United States in response and arrive in the vicinity of the Florida Peninsula during the upcoming weekend. There has been a great amount of variability/ uncertainty in model solutions of exact frontal boundary placement (stall, full passage, etc) from run to run and model member to model member (ensemble vs deterministic). While forecast details for the upcoming weekend will surely become clearer as we progress further into the work week, let's briefly delve into what a stall of the boundary to the north could transpire for our area as opposed to a full frontal passage. A stall of the boundary to the north of South Florida would place the region in the envelope of deep tropical moisture which could facilitate higher than normal rain chances and a continuation of a humid and tropical airmass. The full passage of the frontal boundary to the south of the region could usher in another push of continental dry air into South Florida and daytime forecast temperature near or slightly below average. Cluster analysis still depicts variations in model guidance on the timing/amplitude of the lobe of troughing across the eastern United States during this period, which could have implications on whether the boundary will stall or make a full sweep across the region.

Forecast high temperatures will remain status quo through the end of the work week with values in the upper 80s to low 90s possible each afternoon. The return of moisture advection across the region on Wednesday will result in a gradual increase of nocturnal temperatures across the region, with a possible return to minimum temperatures in the low 80s along the immediate east coast late in the week.

AVIATION
(18Z TAFS)
Issued at 1240 PM EDT Mon Oct 12 2026

VFR condition will prevail at all sites through the period. Winds are expected to shift more NE this afternoon and are beginning too at this hour. Not expecting a threat of SHRA today as any isolated activity should develop inland and away from the terminals today.
Winds may maintain a light breeze out of the NE overnight, and then increase back to around 10 kts tomorrow afternoon.

MARINE
Issued at 127 AM EDT Mon Oct 12 2026

Surface winds will veer northerly this morning in response to a frontal boundary that will gradually push southwards our local waters during the remainder of today. Small Craft Exercise Caution (SCEC) conditions could be realized at times across the Atlantic and Gulf waters today as breezy northerly winds enhance behind the boundary. Waves will remain 2-3 feet across the region through this evening with the caveat that locally higher waves and winds are possible in and around any shower or thunderstorm activity. One or two waterspouts remain possible ahead and along the frontal boundary as it moves southwards across the local waters today.

PRELIMINARY POINT TEMPS/POPS
Miami 75 88 76 88 / 10 10 10 20 West Kendall 74 89 74 88 / 10 0 10 30 Opa-Locka 75 89 76 88 / 10 0 10 20 Homestead 75 89 76 88 / 10 10 10 30 Fort Lauderdale 75 87 76 87 / 10 10 10 20 N Ft Lauderdale 75 88 76 88 / 10 10 10 20 Pembroke Pines 75 88 75 88 / 10 0 10 20 West Palm Beach 73 87 75 88 / 0 10 10 20 Boca Raton 74 87 76 87 / 0 10 10 20 Naples 70 88 71 89 / 0 0 0 10

MFL WATCHES/WARNINGS/ADVISORIES
FL...None.
AM...None.
GM...None.