Live Wet Bulb Globe Temperature for St. John, updated every 15 minutes. Roughly two-thirds national park, St. John is the USVI's hiking island, where the difference between forest shade and an exposed ridge can move WBGT a full threat tier.
Last updated July 9, 2026 · Live data refreshes every 15 min
St. John is the quietest and greenest of the three islands, with about 60% of its land protected as Virgin Islands National Park. That makes it a hiker's island, and hiking is where heat risk concentrates.Cruz Bay, the main town and ferry gateway, is compact and breezy, but the trails inland and along the south shore are a different story.
Two islands in one: shade versus exposure
Under closed forest canopy, much of the interior trail network, the sun's radiant load is blocked and WBGT sits noticeably lower. Step onto an exposed ridgeline, a south-facing descent like the Reef Bay Trail, or an open beach like Trunk Bay, and the globe temperature term jumps as direct sun hits. The same afternoon can be moderate in the trees and high in the open a few hundred yards away. This is exactly the gap WBGT is built to capture and a shade-assuming heat index cannot.
Hiking St. John safely
Go early. Solar load peaks midday; a trail that's manageable at 7 a.m. can be hazardous by 1 p.m. The climb back out is the dangerous half.
Carry more water than you think. There is no resupply on most trails, and the humid canopy masks how much you're sweating.
Respect the exposed stretches. Check the live reading before committing to a long south-facing or ridgeline route, and treat the beach as full-exposure, not a break.
Unacclimatized visitors should downgrade their plans for the first few days, see acclimatization.
Local tip. Use the forest as your air conditioning: plan routes so the exposed, uphill sections fall in the cool early hours and the shaded stretches carry you through midday.
Check your exact trail
Because St. John's heat is so local, the Cruz Bay card above is only a starting point. Open the live map, pin your trailhead, beach, or villa, and read conditions for that spot. If the number is new to you,What is WBGT? explains what you're looking at.
Frequently asked questions
What is the WBGT on St. John right now?
The live card on this page shows current WBGT near Cruz Bay. Trail conditions vary sharply with shade and ridgeline exposure, so open the interactive map and pin your specific trailhead or beach for the closest reading.
Is it safe to hike the Reef Bay Trail in summer?
It can be, early. Reef Bay and other south-facing trails run through long sun-exposed stretches where WBGT climbs fast by midday. Start at first light, carry far more water than feels necessary, and turn back if conditions reach the high band. The uphill return in afternoon heat is the real hazard.
Does the national park make St. John cooler?
In the forest, yes, dense canopy blocks the sun and can hold WBGT a tier lower than an exposed ridge or beach. But the same island has fully exposed trails and coastline, so St. John swings between two very different heat worlds within a short walk.