Straits of Florida from Craig Key to West End of Seven Mile Bridge Out 20 NM Marine Forecast
| This Afternoon...South Winds 10 To 15 Knots. Seas Around 1 Foot. Wave Detail: Southeast 1 Foot At 3 Seconds. Showers Likely With A Chance Of Thunderstorms. |
| Tonight...Southeast To South Winds 10 To 15 Knots. Seas 1 To 2 Feet. Showers Likely With A Chance Of Thunderstorms. |
| Wednesday...South Winds 5 To 10 Knots. Seas 1 To 3 Feet. Showers With A Chance Of Thunderstorms. |
| Wednesday Night...Southeast To South Winds 5 To 10 Knots. Seas 1 To 2 Feet. Showers Likely With A Chance Of Thunderstorms. |
| Thursday...Southwest Winds Near 5 Knots, Becoming Northwest To North. Seas Around 1 Foot. Showers Likely With A Chance Of Thunderstorms. |
| Thursday Night...Northwest To North Winds Near 5 Knots, Increasing To 5 To 10 Knots. Seas 1 To 2 Feet Due To Increasing Northeasterly Swell. A Chance Of Showers And Thunderstorms. |
| Friday...North To Northeast Winds 5 To 10 Knots. Seas 1 To 3 Feet Due To Northeasterly Swell. A Chance Of Showers And Thunderstorms. |
| Friday Night...Northeast Winds Near 5 Knots. Seas 2 To 4 Feet, Occasional 5 Feet. A Chance Of Showers And Thunderstorms. |
| Saturday...Northeast Winds Near 5 Knots. Seas 2 To 4 Feet, Occasional 5 Feet . Showers Likely With A Chance Of Thunderstorms. |
| Saturday Night...Northeast Winds Near 5 Knots. Seas 2 To 3 Feet Due To Decreasing Northeasterly Swell. Showers Likely With A Chance Of Thunderstorms. |
| Area Forecast Discussion National Weather Service Key West FL 322pm EDT Tuesday September 22 2026 Marine Issued at 314pm EDT Tuesday September 22 2026 Convection to afternoon is mostly limited to the Southeast Gulf and far western waters with lesser coverage elsewhere. This lull in the activity will be brief and expecting a renewed surge in showers and thunderstorms this evening and overnight as deep tropical moisture continues to push northward from the western Caribbean. Outside of any passing convection, breezes will generally be light to gentle with the exception of the Straits of Florida, which will see gentle to moderate breezes. Breezes overall will slacken going into the later half of the week in advance of an approaching frontal boundary. Breezes may go light and variable, especially over the waters north of the island chain on Thursday. Thereafter, expecting freshening northerly breezes behind a frontal passage Friday. Issued at 409am EDT Tuesday September 22 2026 The upper level low that we have been tracking the past several days has now opened into a trough as it lifts away from the region off the northeast coast of Florida throughout the day. Remnant energy associated with this departing disturbance will aid in the development of a coastal low that will track in a general northeast direction through the end of the week, deepening as it gains latitude. A cold front attached to this system will push southward into central Florida by Thursday and south Florida into Friday as the low pressure system becomes increasing occluded and retrogrades westward towards coastal New England by the end of the week. Meanwhile, before this frontal boundary approaches our area, we have a wet and stormy weather pattern on tap across the Florida Keys over the next several days. 250 mb analysis is showing a positively tilted trough extending into the Yucatan Peninsula left in the wake of the departing aforementioned disturbance. To the east of this feature, a deep feed of tropical moisture with its source regions in the southwest Caribbean is directed northeastward across Cuba, The Bahamas, and the Florida Keys with PWATs (Precipitable Waters) possibly peaking as high as 2.5 inches either later today or Wednesday. The increasing moisture advection and PVA throughout the day supports rounds of scattered to numerous showers and thunderstorms that will generally drift in a northward direction across the region. Despite these favorable ingredients to support well above normal Probability of Precipitation today (60-80%), the southerly steering flow in place does add some uncertainty to the convective evolution as a Cuban shadow influence could ultimately bring a decrease in overall coverage at times. Current thinking is that forcing for ascent and anomalous moisture should ultimately win the battle so our forecast reflects these likely/categorical Probability of Precipitation but certainly something to mention. The heavy rainfall threat continues on Wednesday as an upper trough axis sharpens across the eastern US, which will help to maintain a tropical moisture connection. If PWATs (Precipitable Waters) are able to reach 2.5 inches, this would be at daily maximum values for this time of the year but even if it is slightly lower, values should still be at or above the 90th percentile of 2.16 inches. Steering flow on Wednesday might also be able to have a slightly more westerly component and this may be just enough to limit the drying influence from Cuba. Additionally, forecast soundings show near saturated atmospheric columns with the classic tall and skinny CAPE appearance so this activity should be very sufficient rain producers with heavy rainfall rates and quick accumulations. Thus, Probability of Precipitation will continue to remain well above normal throughout this time with localized hydro impacts a possibility, particularly during high tide cycles where drainage capacity is less. Overall, Quantitative Precipitation Forecast amounts through Wednesday night could be around 1.5-3 inches across the Florida Keys, which aligns with HREF 50th percentile values. However, should this event exceed expectations, values of 4-6 inches with locally higher totals can't be ruled out, which is shown in several 90th percentile solutions. As a result, WPC highligheights all of the Keys for a Marginal risk of excessive rainfall through Thursday morning. Rain chances will drop a bit closer to climatological values later in the week as aforementioned frontal boundary makes southward progress across the Florida peninsula. Drier air aloft spreads southward in the wake of this frontal boundary on an exceptionally deep northerly flow across the entire eastern CONUS on the backside of the nor'easter in the north Atlantic. However, some Probability of Precipitation may still linger late week and into the weekend as the frontal boundary is expected to stall just north of Cuba in the Straits so the deeper moisture may not be able to completely scour out. Regardless, this frontal passage will certainly still be noticeable despite a much less impressive air mass change compared to what many areas further north will experience. Dewpoints are still projected to drop into the low to mid 70s and coupled with highs in the mid/upper 80s, this will be noticeable after the typical prolonged duration of extreme humidity experienced during Florida summers. However, it is still late September and long range guidance suggests that the slight decrease in humidity levels will be short-lived as return flow setting up early next week allows moisture values to recover and rain chances continuing to persist through the remainder of the forecast period. NOAA Key West FL Office: Watches - Warnings - Advisories FL...None. GM...None. |
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