Florida Keys Overseas Highway

Reservations open eleven months out for the only three RV-capable state parks on the Overseas Highway. Bahia Honda, Long Key, and John Pennekamp all share the Florida State Parks reservation system at 800-326-3521, with booking windows opening at 8:00 a.m. Eastern. Bahia Honda lists 80 sites split across three loops with different rig caps. The Bayside loop, sites 73-80, sits behind the historic Bahia Honda Rail Bridge — 6 feet 8 inches of overhead clearance at the underpass, period (Florida State Parks). Buttonwood handles rigs up to 45 feet on a handful of sites; Sandspur caps at 23 feet hitch-to-bumper. Long Key reopened a 60-site loop with hookups for rigs up to 45 feet at $22 a night plus the $2.50 Monroe County surcharge. John Pennekamp at MM 102.5 holds 47 full-hookup sites with 30/50-amp service, most rated around 40 feet. Outside those three, RV slips on US-1 are private and priced like resorts. Wind on the Seven Mile Bridge runs steady; the 6.79-mile span has no shoulder and no exits, so high-profile rigs cross slow and stay in the right lane.

Elevation, the inverse problem — you are below the storm surge line: The entire Overseas Highway runs 0-18 ft above mean sea level. Big Pine Key tops out at 4 ft AMSL, Marathon at 6 ft, Stock Island at 8 ft. NOAA's SLOSH model projects a Category 3 hurricane producing 9-15 ft of storm surge across the Lower Keys, meaning every campground on this route floods in a direct hit (NOAA National Hurricane Center). FDOT's elevation database (FDOT Roadway Characteristics Inventory) shows the Overseas Highway pavement crown ranges from 6 ft AMSL on the bridge approaches to 22 ft at the Seven Mile Bridge midspan. There is no high ground to retreat to inside Monroe County — your evacuation route is 113 miles north to mainland Florida, and you start moving 48-72 hours before predicted impact.

Bridge clearances and the Seven Mile crosswind problem: The current Seven Mile Bridge (opened 1982) replaced the original 1912 Henry Flagler railroad bridge and carries 36 ft of pavement width across 6.79 miles with no shoulder, no breakdown lane, and no center divider beyond a painted yellow stripe (FDOT District 6). NWS Key West issues a Marine Wind Advisory for the Lower Keys whenever sustained winds hit 25 kt; FDOT closes the Seven Mile Bridge to high-profile vehicles at 39 mph sustained (Beaufort 8) and shuts it completely above 50 mph. Class A coaches over 11 ft tall, fifth-wheels, and any travel trailer over 8 ft 6 in wide should track NWS marine forecast KEY for KZK680 before crossing. The Long Key Bridge (2.3 mi), Bahia Honda Bridge (1 mi), and Niles Channel Bridge (4,500 ft) have the same exposure but are short enough to cross between gusts.

Seasonal window, hurricane math drives everything: NOAA's official Atlantic hurricane season is June 1 through November 30. The Keys average 7.5 named storm threats per year and one direct hit every 4.2 years (NOAA HRD Atlantic basin database 1851-2024). Most RV insurance carriers exclude named-windstorm damage in Florida from June 1 through November 30 unless the policy specifically endorses Atlantic Hurricane coverage — check the declarations page of your own policy, not the marketing brochure. The dry-season window is December 1 to April 15: average highs in the mid-70s F, dew points below 65 F, mosquito populations at annual minimum, and Bahia Honda water visibility above 50 ft. May is hot and humid but pre-hurricane. October is the second-deadliest hurricane month and your reservation is non-refundable inside 72 hours.

Fuel, water, dump — bridges between everything: Diesel pumps that fit a 40 ft coach: Florida City (last mainland stop on US-1), Key Largo (Shell at MM 100 and Tom Thumb at MM 99), Islamorada (Shell at MM 84), Marathon (Mobil at MM 51 and Marathon Express at MM 49), Big Pine (Shell at MM 30), Stock Island (Marathon at MM 5), Key West (Sunoco at White Street). Note: Sandspur Loop at Bahia Honda does not accept rigs over 23 ft, so the dump station is your sole stop unless you booked Buttonwood ($55-65/night, hookup). Pennekamp has dump at the campground entrance loop. Long Key has dump at the entry station. Carry 30+ gallons of fresh water minimum — heat and salt air drive consumption to 5 gallons per person per day.

Cell coverage and the marine-band gap: Verizon dominates the corridor with usable LTE end-to-end except a 2-mile gap at Niles Channel Bridge (MM 30). AT&T has solid coverage at every named key but drops to 1 bar across the Seven Mile Bridge midspan. T-Mobile improved markedly in 2025 (deployed on FirstNet tower at Bahia Honda) but still has dead zones on Long Key and Lower Sugarloaf. NOAA Weather Radio KEC-50 (162.4 MHz) at Big Pine Key broadcasts NWS Key West forecasts 24/7 — buy a $30 emergency radio for the trip; cell goes down with the first squall line.

Primary sources beyond what's footnoted below: NWS Key West marine forecast at weather.gov/key (KZK675-680 zones), Monroe County Office of Emergency Management evacuation phases at monroecountyem.com, FDOT high-wind bridge protocols at fdot.gov/maintenance/bridges, Florida State Parks reservation system at floridastateparks.org/reserve (call 800-326-3521 at exactly 8:00 am Eastern for sniper-bookings), and Florida Keys National Marine Sanctuary boater regs at floridakeys.noaa.gov for the coral-anchoring ban inside Sanctuary Preservation Areas.