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

DISCUSSION
Issued at 208 AM EDT Sat Apr 19 2025

Today-Tonight...Surface high pressure consolidates over the western Atlantic today, with upper level ridging building into the local area. Meanwhile, the ridge axis settles across Georgia and South Carolina. Locally, onshore flow will continue, enhancing slightly today as the high pressure strengthens to the north.
Winds 10-15 mph today across most of east central Florida will increase to 15-20 mph this afternoon along the coast as the sea breeze develops. This feature will lead to wind gusts 20-25 mph as it moves inland through the afternoon hours. Dry conditions are forecast to continue, which, combined with breezy winds, will cause sensitive fire weather conditions to persist (see below section for more details). Winds will decrease this evening into tonight, though could remain up to 5-10 mph along the coast. Highs this afternoon in the low to mid-80s, with overnight lows in the 60s.

Sunday-Next Week...High pressure continues over the western Atlantic through at least mid-week, while slowly drifting towards the Florida peninsula. Dry conditions persist, as do fire weather concerns. Daily sea breezes will enhance onshore flow in the afternoons. However, by Tuesday, even onshore flow will struggle to provide relief from increasing temperatures. Heat looks to become an increasing concern, as temperatures become above normal.
Highs are forecast to reach the upper 80s west of Orlando by Sunday. Then, lower 90s are expected early next week for most of the interior, with mid-80s along the coast. A few record highs could be threatened, especially Tuesday and Wednesday. Overnight lows in the 60s.

By late week, the ridge manages to repel any frontal passages.
However, it is forecast to be weakened by a passing upper level shortwave mid-week, shifting the surface high northeastward away from the local area. Generally dry conditions persist, though a slight chance (~20%) for showers returns to the forecast late week into the weekend along and offshore from the Treasure Coast, with the ridge axis once again north of the area. Hot afternoon highs in the mid-80s to lower 90s are expected to continue into next weekend.

MARINE
Issued at 208 AM EDT Sat Apr 19 2025

Poor boating conditions over the Gulf Stream waters south of Cape Canaveral today and tonight, due to easterly winds up to 15-20 kts. Small craft should exercise caution over the Treasure Coast and offshore Brevard County waters. East to southeast winds 10-15 kts are forecast to continue through at least mid-week next week.
Seas 4-5 ft today into tonight diminishing to 3-4 ft through the remainder of the period.

AVIATION
(06Z TAFs)
Issued at 137 AM EDT Sat Apr 19 2025

VFR continuing through the period. East winds around 5-10 kts at most coastal terminals through sunrise. Otherwise, variable winds around 5 kts across the interior and at DAB early this morning.
Gusty east winds increase by 14Z at all sites. Max sustained winds forecast around 15-20 kts this afternoon with peak gusts around 25-28 kts. Dry conditions persist.

FIRE WEATHER
Issued at 208 AM EDT Sat Apr 19 2025

Very sensitive fire weather continues, with near Red Flag conditions possible over the interior this afternoon. Onshore flow will persist through the weekend, becoming breezy and gusty in the afternoons as the sea breeze develops and moves inland. No precipitation forecast to relieve continued drying of fuels.
Highest wind speeds are expected to occur near the coast, where min RH is forecast above critical levels. Winds 10-15 mph west of I-95 and 15-20 mph along the coast this afternoon, with gusts 20-25mph. Min RH between 35-45% over the interior and 45-50% along the coast. Will need to monitor Lake County today, as this will be the most sensitive area this afternoon, especially if winds overperform.

Sunday, southeast winds relax slightly, but remain 10-15 mph, with gusts up to 20 mph in the afternoon. Min RH continues between 35-45% over the interior counties and 45-55% for coastal areas. Very good to excellent dispersion each day. Very similar conditions look to continue through early next week, with increasing heat concerns.

PRELIMINARY POINT TEMPS/POPS
DAB 81 63 82 65 / 0 0 0 0 MCO 85 64 86 65 / 0 0 0 0 MLB 80 68 81 67 / 0 0 0 0 VRB 80 66 82 66 / 0 0 0 0 LEE 87 62 88 65 / 0 0 0 0 SFB 85 62 86 64 / 0 0 0 0 ORL 85 64 86 66 / 0 0 0 0 FPR 80 66 83 66 / 0 0 0 0

MLB WATCHES/WARNINGS/ADVISORIES
FL...None.
AM...None.