St. Augustine in August: Weather, Sea Temperature and Hurricane Season

ST. AUGUSTINE · AUGUST · EASTERN TIME

An average August day in St. Augustine reaches 90.8°F, and the ocean off the beach sits at 84.0°F. That pairing sets the shape of the day: fort and old streets in the morning, indoors through the middle of the afternoon, water and dinner in an evening that keeps its light until after eight.

August also sits inside hurricane season. The season runs June 1 to November 30 and turns active from mid-August onward, with its statistical peak on September 10. Rain reaches the ground on 10.3 days in an average month, and 2.0 of those bring an inch or more. That does not rule the month out. It does change how you book, and it moves the good hours to either end of the day.

On this page

• How hot St. Augustine gets in AugustHighs of 90.8°F, lows of 73.4°F, 10.3 rain days
• Can you swim in August?Sea at 84.0°F, measured as daily maxima
• Crowds, prices and the lodging tax5% county tax on top of 6% state sales tax
• Things to do when the air is at 90°FCastillo de San Marcos and Fort Matanzas
• A two-day plan for AugustFort at 9:00 a.m., beach at four, dinner after eight
• August, July or SeptemberHow the three months compare on heat, rain and water
• Is August a good time to go?Who should book, and who should wait for the dry season

What August changes in St. Augustine is the air, the water and the storm odds. The month before runs a degree hotter by day, and the July page carries its numbers. The twelve-month view belongs to our Florida timing guide, and the wider state sits in our Florida orientation.

St. Augustine weather in August: average highs, lows and rain days

Every figure here comes from NOAA NCEI’s 1991–2020 monthly normals for station USW00013889, a real instrument with a real identifier, sitting at Jacksonville International Airport rather than in the old town. On that record an average August day tops out at 90.8°F, bottoms out at 73.4°F, and the month collects 6.88 inches of rain. A reanalysis of a grid cell would give slightly different values, and the two are not the same measurement.

Rain arrives on 10.3 days in an average August, counting days that record at least 0.10 inch, and 2.0 of those deliver an inch or more. A good share of the month’s 6.88 inches falls on that pair of days. Call it one day in three with something measurable, in the wet half of Florida’s year, since the statewide dry season runs November through April. Keep the outdoor hours in the morning, keep one indoor plan in reserve for mid-afternoon, and the rain count stops steering the trip.

The spread between the 90.8°F high and the 73.4°F low is 17.4 degrees, and the low lands near dawn, so the evening stays warm long after sunset. No sweater goes in the bag. A packable rain shell does, along with a hat, a spare shirt for the walk back and a bottle you can refill. Our know-before-you-go guide covers the rest of the Florida kit.

On August 15 the sun rises at 6:52 a.m. and sets at 8:07 p.m. Eastern time, for 13 hours 15 minutes of daylight. St. Augustine keeps Eastern time with Orlando, Tampa and Miami, since only the western Panhandle runs on Central. That late sunset is what makes the heat workable. The Castillo de San Marcos empties at 5:15 p.m., and close to three hours of daylight are still waiting when it does.

Can you swim in St. Augustine in August? Sea temperature and what the water feels like

The sea off St. Augustine averages 84.0°F in August, from the Open-Meteo Marine record for 2015 to 2024. One caveat travels with that number: it is the mean of daily maximum readings, not a 24-hour average, so it sits a shade above what a round-the-clock mean would give. Tables that average over the full day will read a degree or so lower for the same water, and neither figure is wrong.

At 84.0°F nobody works up to it from the edge, and nobody needs neoprene. Children stay in until somebody calls them out. The catch is that the water sits only 6.8 degrees below an average afternoon of 90.8°F, so a swim cools you for about as long as the walk back to the towel takes. Late afternoon beats noon for that reason: the sun is lower, and the water has not moved.

We could not verify wind or swell averages for August, so we give none. The calendar is verified: the Atlantic hurricane season runs June 1 to November 30 and peaks on September 10, with most activity between mid-August and mid-October, which puts the back half of the month inside the busy stretch. Read the flags before you go in. Double red means the water is closed, red high hazard, yellow medium, green low, purple dangerous marine life. No Florida law compels a beach to fly any of them, and our Florida safety guide explains what that silence means.

How busy is St. Augustine in August? Crowds, prices and the lodging tax

We found no occupancy series and no monthly room-rate data for St. Augustine, so we crown no month cheap or expensive. The calendar facts are firm enough to plan on. Florida’s dry season runs November through April, the stretch the state sells hardest, and August sits at the far end of the year, inside the hurricane window. Fixed costs ignore all of that. The Castillo de San Marcos charges $15 for visitors aged 16 and up in August exactly as in February, and Fort Matanzas is free the whole year.

So the cancellation policy matters more than the booking date. We have no lead-time data for the town, and we will not invent a number of weeks. A room you can cancel without charge costs nothing if a storm forms in the second half of the month, and a non-refundable one costs the whole stay. Check the National Hurricane Center’s outlook in the week before you fly, and keep the airline’s change rules filed next to the hotel’s.

On the bill, St. Johns County levies a 5.0% transient rental tax, filed and paid with the 6% state sales tax, per the Florida Department of Revenue’s form DR-15TDT. Together that is 11% on the room before any property charges. It applies in August exactly as in January, so it is a budget line rather than a summer penalty. We verified no hotel names and no nightly rates here, so we give no example bill. Our Florida cost guide handles the wider budget.

Where spending more genuinely changes an August day is distance. A base within walking range of the old town turns the two o’clock retreat indoors into five minutes instead of a drive and a parking hunt. The Castillo ticket runs the same logic in reverse: $15 buys 7 consecutive days, so a 9:00 a.m. visit on Monday and a second look on Wednesday cost the same as one. Children 15 and under enter free with an adult, and that makes the fort one of the cheapest hours of a family day.

Things to do in St. Augustine in August: Castillo de San Marcos and Fort Matanzas

August is the month when the water and the evening line up. The sea at 84.0°F is within half a degree of July’s 84.5°F and above September’s 83.7°F, and the daylight on August 15 holds until 8:07 p.m. A fort at nine, lunch indoors, a swim at five and a late dinner all fit in a single day without anyone hurrying. Try that sequence in a month with an earlier sunset and something has to be dropped.

St. Augustine holds two of Florida’s eleven National Park Service units, and neither carries the National Park designation. The Castillo de San Marcos is the oldest masonry fortification in the continental United States, in the Park Service’s careful wording, built of coquina because it was the only local stone the Spanish had. Admission is $15 for anyone 16 or over, free for children 15 and under with an adult, first entry 9:00 a.m., last entry 5:00 p.m., everyone out by 5:15, seven days a week. Fort Matanzas preserves a coquina watchtower completed in 1742.

What August alters at both forts is the air around them, never the stone. Coquina that has stood since 1742 is indifferent to 90.8°F, but a masonry fort in full sun at two in the afternoon is not, and that 9:00 a.m. first admission is the coolest ticket of the day. The St. Augustine Lighthouse keeps its summer schedule through September 30, 9:00 a.m. to 6:30 p.m. with the last ticket at 6:00 p.m., a half hour later than the October to February hours. The 1874 tower climb comes with general admission, though we could not read the admission price.

Fort Matanzas costs nothing, the ferry included. The boarding pass is free too, but you collect it at the Fort Matanzas Visitor Center rather than the city visitor center in town, and every member of the family needs one whatever their age. The ferry service runs October 1 to September 30. Ask at the desk for the daily departure times when you collect your passes. Beach walking is free as well, with one wrinkle from Florida Statutes 163.035: wet sand below the mean high-water line is public, and dry sand above it can be private.

St. Augustine in August: a two-day itinerary

Day one starts early because the light does. Sunrise is 6:52 a.m., so breakfast by eight puts you at the Castillo de San Marcos for the 9:00 a.m. first admission, $15 and good for seven days. Give the fort and the streets around it until noon, then eat indoors and stay there through the worst of the 90.8°F. Come back out at four for the beach and its 84.0°F water. Dinner can run late, since the sun holds until 8:07 p.m.

Day two goes south to Fort Matanzas. Collect the free boarding passes at its visitor center on arrival, one per person, then ride the ferry across to the 1742 watchtower. The afternoon belongs to the St. Augustine Lighthouse, open until 6:30 p.m. with the last ticket at 6:00 p.m., where the tower climb is part of general admission and children under 44 inches stay at the bottom. If a storm rolls through, the seven-day fort ticket earns its second use: back to the Castillo the next morning at nine, at no extra cost.

St. Augustine in August vs July and September

Across the three months the numbers move less than the reputations do. July runs 91.9°F by day against August’s 90.8°F, a gap nobody feels, while September drops to 87.2°F and takes the nights with it, from 73.4°F down to 70.5°F. Rain runs the other way: September collects the most water, 7.56 inches, on the fewest days, 8.4, against August’s 6.88 inches spread over 10.3. The sea hardly joins in at all, 84.5°F in July, 84.0°F in August, 83.7°F in September, less than a degree across the quarter.

Shift four weeks later and you take 3.6 degrees off the average afternoon, lose two wet days and give up three tenths of a degree in the water. What you take on is the date, because September 10 is the statistical peak of the season and the month carries the heaviest rainfall of the three. Shift four weeks earlier into July instead and you pay 1.1 degrees of heat for half a degree of extra sea warmth. Of the two moves, only the September one really changes a trip, and it changes the insurance question with it.

Is August a good time to visit St. Augustine?

Yes, if the point of the week is water and long evenings. An 84.0°F ocean, an 8:07 p.m. sunset and two federal forts that open at nine make a solid family stretch. No, if the plan involves a full day on foot through the old town in the middle of the afternoon, or if you need to lock in a non-refundable room for the second half of the month, when the hurricane window is already running hot.

If the heat is what stops you, September is the nearest relief at 87.2°F and 8.4 wet days instead of 10.3, with the September 10 peak sitting right in the middle of it. If the storms worry you more than the thermometer, the answer lives in the other half of the calendar: the Florida dry season runs November through April, and our timing guide argues it month by month. We have no November sea temperature for St. Augustine, so we promise nothing about swimming then.

What August offers that neither neighbor does is July’s water at a degree less of July’s heat, ahead of the September 10 peak, with the light still on at eight in the evening.

The last word

Book the room you can cancel, then set the alarm. August works when the day opens at nine at the Castillo and the swim waits until four. One more number for the flight file: Jacksonville JAX, the nearest large airport, boarded 3,749,791 passengers in 2024 against Orlando MCO’s 27,859,783, so a cheaper fare may put you at the busiest one instead, and we did not check the drive between them. And if someone calls this the country’s oldest city, the Park Service pages we read date the founding to 1565 and leave the superlative alone.

Sources & data for this guide

• August normals, rain-day counts and the July and September figures · NOAA NCEI monthly normals 1991–2020, station USW00013889 (Jacksonville International Airport) · checked Sep 23, 2026
• Sea surface 84.0°F, mean of daily maxima 2015–2024 · Open-Meteo Marine API · checked Sep 23, 2026
• Sunrise 6:52 a.m., sunset 8:07 p.m. and 13 h 15 min of daylight on Aug 15 · sunrise-sunset.org, UTC converted to Eastern time · checked Sep 23, 2026
• Hurricane season dates, the September 10 peak and the mid-August to mid-October window · NOAA National Hurricane Center · checked Sep 23, 2026
• Castillo de San Marcos fees, hours and coquina construction · National Park Service · checked Sep 7 and 8, 2026
• Fort Matanzas free entry, boarding passes, ferry season and the 1742 watchtower · National Park Service · checked Sep 23, 2026
• Transient rental tax of 5.0% in St. Johns County with the 6% state sales tax · Florida Department of Revenue, form DR-15TDT · checked Sep 23, 2026
• Lighthouse hours and the 44-inch tower rule · St. Augustine Lighthouse & Maritime Museum · checked Sep 23, 2026. We could not read a general admission price, so we give none.
• Beach warning flags and beach access above the mean high-water line · Florida Statutes s. 380.276 and s. 163.035, Volusia County Beach Safety · checked Sep 23, 2026
• Airport boardings, CY2024 · Federal Aviation Administration · checked Sep 23, 2026
• We found no occupancy or room-rate series for St. Augustine, so we rank no month by price. We could not read the Fort Matanzas ferry departure times, and we verified no August event dates, so we name none.

To plan your stay

• Things to Do in St. Augustine: Castillo Tickets, Fort Matanzas Ferry and Lighthouse Hours
• Where to Stay in St. Augustine: Historic District, the Beach and the 5% Lodging Tax
• Airport to St. Augustine: JAX, MCO, Rental Cars and Eastern Time
• St. Augustine Know Before You Go: Castillo Fees, the Fort Matanzas Ferry Pass and Beach Rules

Nearby places

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• Silver Springs, Florida: Glass-Bottom Boats, No Swimming Area, 1,686 Parking Spaces
• Blue Spring, Florida: Water Temperature, Swimming and Parking Limits