Marine Weather and Tide Forecast for Brunswick, GA

SYNOPSIS
Issued at 405 AM EDT Sat Jun 21 2025

Overnight surface analysis depicts Atlantic high pressure (1023 millibars) centered near Bermuda, with this feature extending its axis west-southwestward across north central FL. Meanwhile, a frontal boundary was dissipating over the southeastern states.
Aloft...deep-layered ridging centered over the lower Mississippi Valley was expanding into the southeastern states. Latest GOES- East derived Total Precipitable Water imagery indicates that an unseasonably dry air mass has advected into our region, with PWATS across southeast GA only around 1 inch, with values along the Interstate 10 corridor around 1.25 inches. PWATs were a little closer to late June climatology for locations in north central FL to the south of Gainesville and St. Augustine, where values were in the 1.6 - 1.8 inch range. A narrow ribbon of deeper moisture exists along the Interstate 4 corridor in central FL, where PWAT values were closer to 2 inches. Fair skies prevail across our region as earlier debris cloud cover continues to thin out, with calm winds inland allowing temperatures and dewpoints to fall to the upper 60s and lower 70s at most inland locations as of 08Z, while coastal temperatures were generally in the mid to upper 70s.

NEAR TERM
(Today and Tonight)
Issued at 405 AM EDT Sat Jun 21 2025

Ridging aloft will continue to expand into the southeastern states and the Tennessee Valley today, while Atlantic surface ridging builds northward across our area. Low level flow will become east- southeasterly this afternoon, which will shift the ribbon of deeper moisture currently in place across central FL back across north central FL this afternoon and evening. This increase in low level moisture should foster scattered convective development during the mid-afternoon hours along inland moving mesoscale boundaries such as the Atlantic and Gulf coast sea breezes for locations south of the Interstate 10 corridor. An unseasonably dry air mass will likely limit convective development later this afternoon, and temperatures at inland locations will soar to the mid 90s across the Suwannee Valley and inland southeast GA, where dewpoints will fall into the 60s this afternoon, keeping maximum heat index values around or just below 100.

Ridging aloft building into the southeastern states will shift steering flow to northeasterly, and scattered convection developing during the mid-afternoon will become focused across southern portions of the St. Johns River basin and north central FL by the late afternoon, where colliding mesoscale boundaries could allow for a few storms to pulse and become strong during the late afternoon or early evening hours. Dry air aloft will increase downdraft CAPE values to around or in excess of 1,000 j/kg this afternoon across north central FL, which may allow pulsing storms to produce downburst wind gusts of 40-55 mph, along with frequent lighting strikes. Slow storm motion across north central FL may result in localized flooding, especially at urban locations such as Ocala and Gainesville. Otherwise, a steady onshore breeze developing at coastal locations this afternoon in the wake of the inland moving sea breeze will keep highs in the upper 80s to around 90 at area beaches, while low to mid 90s prevail across inland northeast and north central FL. Dewpoints remaining in the lower 70s will result in maximum heat index values of 100-105.

Early evening convection over north central FL and southern portions of the Suwannee Valley will shift west of the Suwannee River shortly after sunset. Debris cloud cover will thin out overnight, allowing lows to again fall to the upper 60s and lower 70s at inland locations, while an onshore breeze keeps coastal lows in the mid to upper 70s. Atlantic surface ridging lifting northward will place our area in a deeper low level onshore flow pattern by sunrise on Sunday, which should allow scattered showers and a few isolated thunderstorms to develop over the Atlantic waters during the predawn hours. An isolated coastal shower or two cannot be ruled out around sunrise on Sunday, mainly for locations south of St. Augustine.

SHORT TERM
(Sunday through Monday night)
Issued at 405 AM EDT Sat Jun 21 2025

As drier air continues to filter into the area, chances of precipitation will begin to trend downward into the upcoming week.
Easterly onshore flow will allow for the Atlantic sea breeze to move well inland on both Sunday and Monday afternoons. The moist marine air may be enough to allow for some shower and storm development as the sea breeze moves inland and meets with the Gulf breeze. With drier air over locations north of the I-10 corridor into SE GA, most activity will likely be along the north central FL counties and western locations of NE FL.

Daytime highs will be in the lower/mid 90s for most areas and upper 80s at the beaches. Overnight lows will be a little above normal in the mid 70s along the coast and low to mid 70s inland.
Heat index values will top out in the 100-105 degree range.

LONG TERM
(Tuesday through Friday)
Issued at 405 AM EDT Sat Jun 21 2025

The weather pattern from the weekend will remain in place through much of the upcoming week. Onshore easterly flow will allow for the Atlantic sea breeze to continue to make its way well inland each day as a ridge of high pressure sits over the eastern CONUS.
Guidance continues to show a lowering trend in PoPs into midweek as dry air will continue to filter into the area, keeping any chances of showers and storms development at a minimal. This will also lead to sunny days during the week ahead, which will allow for temps to rise into the mid/upper 90s for inland locations, with temps steadily increasing towards the end of the week.
Onshore flow will keep coastal locations in the lower 90s. By the end of the week, the high pressure will start to weaken, opening the door for a return of moist air from the Atlantic and an increase in PoPs for NE FL.

AVIATION
(12Z TAFS)
Issued at 701 AM EDT Sat Jun 21 2025

Drier airmass in place will continue below normal convective activity today with best chances across North Central FL as some moisture tries to lift northward, and for now will keep PROB30 groups in place this afternoon for GNV in the 20-24Z time frame.
Otherwise VFR conds tonight as well with the usual chance for patchy MVFR fog at VQQ late tonight.

MARINE
Issued at 405 AM EDT Sat Jun 21 2025

Atlantic high pressure centered near Bermuda will lift its axis northward across our area today, with high pressure then becoming situated off the southeastern seaboard through the middle portion of the upcoming week. Onshore winds will prevail across our local waters during the next several days, with only isolated to widely scattered showers and thunderstorms forecast, mainly across the northeast Florida waters. High pressure will then weaken and shift southward across our area late next week, with gradually increasing chances for showers and thunderstorms expected by Friday. Seas of 2 to 3 feet will prevail both near shore and offshore during the next several days.

Rip Currents: Persistent onshore winds will combine with an east- southeasterly ocean swell to create a lower end moderate risk at all area beaches during the next several days.

FIRE WEATHER
Issued at 405 AM EDT Sat Jun 21 2025

Light south to southwesterly surface and transport winds this morning will shift to east-southeasterly during the afternoon hours, with breezy surface speeds developing along the I-95 corridor. These winds will combine with elevated mixing heights to create fair to good daytime dispersion values inland, with fair values forecast at coastal locations. Easterly transport winds are forecast area-wide from Sunday through Wednesday, with breezy surface speeds developing across northeast and north central FL each afternoon. These winds will combine with elevated mixing heights to create good daytime dispersion values at inland locations on Sunday and Monday, with fair values at coastal locations. Marginally high values will be possible across north central FL and portions of the Suwannee Valley on Monday afternoon. Afternoon and early evening thunderstorm activity will be confined to locations south of Interstate 10 this weekend and will then become isolated for locations south of I-10 during the early and middle portions of the upcoming week, with an unseasonably lengthy stretch of dry weather prevailing through at least midweek across southeast GA.

PRELIMINARY POINT TEMPS/POPS
AMG 95 71 94 70 / 10 10 20 10 SSI 88 77 87 77 / 10 0 10 10 JAX 94 73 92 73 / 20 0 20 10 SGJ 90 74 89 75 / 20 10 20 10 GNV 95 72 94 73 / 50 10 30 10 OCF 94 72 95 73 / 60 20 40 10

JAX WATCHES/WARNINGS/ADVISORIES
FL...None.
GA...None.
AM...None.