Sun Safety in Guam

Guam's tropical latitude creates extreme ultraviolet radiation year-round. Unlike temperate destinations where UV varies by season, in Guam the risk stays dangerously high every day of the year.

• UV index of 11+ means extremely high risk of skin and eye damage even in short exposures.
• Clouds only reduce UV by roughly 25% — always wear sunscreen even on overcast days.
• Water and sand reflect UV rays, increasing total exposure by up to 80% compared to being in shade.
• The "shadow rule": if your shadow is shorter than your body, UV is at dangerous levels.
• Guam's humidity amplifies heat stress — the "feels like" temperature regularly exceeds 38°C (100°F).

Choosing the right sunscreen and applying it correctly is your primary defense against UV damage in Guam.

• Use SPF 50+ broad-spectrum (UVA + UVB) sunscreen on all exposed skin daily.
• Choose reef-safe sunscreen (free from oxybenzone and octinoxate) to protect Guam's coral reefs.
• Apply sunscreen 20–30 minutes before going outdoors so it can fully absorb.
• Reapply every 2 hours — more frequently if swimming or sweating heavily.
• Don't miss: lips (SPF lip balm), ears, back of neck, and tops of feet.
• UV-protective rash guards (UPF 50+) offer more consistent protection than sunscreen alone.
• Wide-brim hats shade your face, neck, and ears from direct sun.
• UV-blocking sunglasses protect against cataracts and UV-induced eye damage.

Heat-related illness is a real risk for tourists in Guam. Knowing the difference between heat exhaustion and heat stroke can save a life.

• Heat exhaustion: heavy sweating, weakness, cool/pale/moist skin, weak pulse, nausea.
• First aid for heat exhaustion: move to shade, loosen clothing, apply cool wet cloths, give sips of water.
• Heat stroke: confusion, hot/red/dry skin, rapid pulse, NO sweating, possible unconsciousness — this is a medical emergency.
• If heat stroke is suspected, call 911 immediately and cool the person by any means possible.
• Most at-risk: elderly people, young children, and those with heart or circulatory conditions.
• Alcohol significantly increases heat exhaustion risk — avoid drinking during outdoor activities in the heat.

• Drink at least 2–3 liters (8–12 cups) of water daily when outdoors in Guam.
• Coconut water is a readily available natural source of electrolytes — excellent for beach days.
• Pale yellow urine = well-hydrated. Dark yellow or orange = dehydrated; drink more water.
• Avoid excessive caffeine and alcohol, which act as diuretics and worsen dehydration.
• Sports drinks can help replenish electrolytes during prolonged physical activity in the heat.

• Early morning (before 10am) is ideal for beach visits, hiking, and outdoor sightseeing.
• Late afternoon (after 4pm) is the second-best window for extended outdoor time.
• Midday (11am–2pm) has peak UV intensity — seek shade or stay indoors during this window.
• Snorkeling and water tours are best in the morning for calmer sea conditions and lower UV.
• Being in the water does NOT protect you from UV — wear a rash guard and apply waterproof sunscreen.