Marine Weather and Tide Forecast for Port St. John, FL

DISCUSSION
Issued at 320 PM EDT Thu Mar 19 2026

Current-Friday...Troughing in the mid-levels remains in place across the eastern US, with shortwaves rounding the southern flank across the Florida peninsula. This energy aloft in combination with a plume of moisture situated across the area resulting from a stalled boundary across Cuba and the Bahamas has supported isolated to scattered shower development across the local Atlantic waters, with some of this activity moving onshore primarily from the Cape southward. Rain chances remain between 20-30% along the coast, with the best rain chances shifting towards across the Treasure Coast tonight. Friday, a strengthening shortwaves moves across Florida, helping to finally push the stalled boundary southward. This will one again support isolated to scattered shower development across the local waters and isolated activity moving onshore cannot be ruled out, especially along the Treasure Coast. Isolated storm development will also be possible across the local Atlantic waters, but chances remain low (20%).

A tight pressure gradient remains in place across east central Florida due to the area being wedged between the stalled boundary and an area of high pressure across the southeastern US. The result has been persistent north to northeast winds of 15 to 20 mph gusting to 30 to 35 mph, with the strongest winds focused along the coast. These winds are forecast to persist over the next couple of hours, with intensity waning into the overnight hours.
Another day of breezy and gusty conditions are forecast into Friday, with the strongest winds once again favored along the coast and barrier islands. These winds will also lead to continued hazardous beach conditions, with a high risk of rip currents persisting through Friday. Entering the surf is not advised!

Afternoon highs remain on track to reach the upper 60s along the coast north of the Cape and into the low to mid 70s elsewhere.
Tonight, lows fall into the upper 40s north of the I-4 corridor and into the 50s elsewhere. Friday, temperatures reach near-normal values for this time of year across east central Florida, with highs generally in the 70s areawide.

Saturday-Monday...High pressure gradually builds across the Florida peninsula through this weekend, allowing for a drier air mass to settle across east central Florida. This will result in near-zero rain chances through this weekend and into early next week as well as clearer skies. The clearer skies will allow for sufficient daytime heating, causing a gradual warming trend in temperatures. Afternoon highs are anticipated to climb into the mid to upper 80s by Monday, with values approximately 5 to 7 degrees above normal. Lows will also trend warmer through this weekend, reaching the mid to upper 50s by Monday night.

With the high sitting overhead, winds are anticipated to be lighter at 5 to 10 mph during the daytime, with some local enhancement possible along the coast as the east coast sea breeze develops and moves inland. Overnight, winds are forecast to be light and variable to calm at times. This would favor the potential for some patchy fog development, especially across the interior portions of east central Florida on Saturday morning and Sunday morning. Confidence in this does remain low, but will continue to closely monitor trends.

Tuesday-Thursday...By Tuesday, a slow-moving cold front approaches Florida, resulting in increasing moisture across the peninsula. The front transitions into more of a stalled boundary mid to late week, with a plume of moisture remaining situated across the peninsula. This will reintroduce low rain chances across east central Florida, generally between 20 to 30 percent.
At this time, there is too low confidence to definitively say whether storms will be possible, but will continue to closely evaluate. High temperatures are forecast to remain above normal through the extended forecast period, with overnight lows remaining right near normal values.

MARINE
Issued at 320 PM EDT Thu Mar 19 2026

Poor to hazardous boating conditions persist across the local Atlantic waters through at least Friday. North to northeast winds of 15 to 25 knots today and into tonight will support seas of 6 to 11 feet, and a Small Craft Advisory remains in effect across all legs of the local Atlantic waters through at least 10 PM. Winds begin to diminish slightly to around 10 to 20 knots tonight, with seas responding by gradually subsiding to 6 to 9 feet tonight and 5 to 7 feet into Friday, with the highest seas focused across the Gulf Stream waters. In addition to the poor to hazardous conditions, isolated to scattered showers and isolated storms will be possible across the local waters tonight into Friday.

By Saturday, high pressure builds over the Florida peninsula and the local Atlantic waters, remaining in place into early next week. Boating conditions improve and become generally favorable once again through the weekend and into early next week. Winds diminish to 5 to 10 knots and seas subside to 2 to 5 feet, with dry conditions prevailing through Monday.

AVIATION
(00Z TAFs)
Issued at 734 PM EDT Thu Mar 19 2026

Mainly VFR conditions at ECFL terminals through the TAF period.
Onshore moving SHRA in band of higher moisture INVOF KVRB-KSUA expected to continue producing TEMPO MVFR VIS/CIG reductions.
Current trends favor impacts to lessen by around 01Z, but some CAMs show this activity could persist through 04Z, and a couple even ramp up SHRA coverage after 04Z. Winds in this SHRA have actually been much lighter (8-12 kts) than background winds, which remain breezy/gusty 10-15 kts with gusts to 20-25 kts at inland terminals, and 15-20 kts with gusts 20-30 kts at coastal terminals from the NNE as of 00Z. Winds settle a bit overnight after 03Z, then pick back up again Friday. Currently have less windy conditions in the TAFs than was seen today, but there is potential for a repeat of gusts over 25 kts, particularly along the coast. Drier conditions by Friday morning, but can't rule out a brief SHRA grazing the coast.



FIRE WEATHER
Issued at 320 PM EDT Thu Mar 19 2026

Sensitive fire weather conditions will continue across east central Florida due to critical minimum RH values. Breezy north to northeast winds continue through at least Friday, with wind speeds of 10 to 15 mph and gusts to 25 mph possible at times, especially along the coast. Wind decrease into the weekend as high pressure situates itself overhead. With the high pressure across the area, temperatures are anticipated to trend warmer this weekend and into early next week, which will help further dry finer fuels. Caution should be taken over the next several days to prevent fire starts, including properly discarding cigarettes, avoiding parking vehicles on dry grass, and avoiding burning outdoors. Fire weather conditions do not look to improve until the middle of next week as moisture increases our ahead of a frontal boundary.

PRELIMINARY POINT TEMPS/POPS
DAB 54 72 50 80 / 0 0 0 0 MCO 54 75 53 81 / 0 0 0 0 MLB 59 74 56 78 / 10 10 0 0 VRB 60 74 57 78 / 30 10 10 0 LEE 49 76 51 81 / 0 0 0 0 SFB 52 75 51 82 / 0 0 0 0 ORL 54 76 53 82 / 0 0 0 0 FPR 58 75 54 78 / 30 10 10 0

MLB WATCHES/WARNINGS/ADVISORIES
FL...None.
AM...Small Craft Advisory until 10 PM EDT this evening for AMZ550.

Small Craft Advisory until 3 AM EDT Friday for AMZ552.

Small Craft Advisory until 8 PM EDT Friday for AMZ555-570-572- 575.