What Is Vog in Hawaii? (Air Quality Guide for Visitors)

**Vog** = **volcanic + fog**. It's the haze created when sulfur dioxide (SO₂) and other gases from **Kīlauea volcano** mix with sunlight, oxygen, dust, and water vapor. The result: a greyish-white haze that can blanket parts of Hawaiʻi for days at a time. ## The short version - **Source:** Kīlauea on Hawaiʻi Island (Big Island) - **Affected most:** Kona side of Big Island, then south Maui, then Oʻahu when winds shift - **When it's bad:** When **kona winds** (from the south/southwest) replace the usual northeast trades - **Who should care:** Asthma, COPD, heart disease, pregnant women, infants, anyone sensitive to air pollution - **Live air quality:** [airnow.gov/hawaii](https://www.airnow.gov/?city=Hilo&state=HI) or [vmap.hivo.org](https://vmap.hivo.org) ## Is it bad right now? Check **[airnow.gov/hawaii](https://www.airnow.gov/?city=Hilo&state=HI)** — the U.S. EPA monitoring stations report in real-time. Look for SO₂ and PM2.5 readings. | AQI | What it means | Visitor advice | |---|---|---| | 0–50 (green) | Good | No restrictions | | 51–100 (yellow) | Moderate | Sensitive groups ease outdoor exercise | | 101–150 (orange) | Unhealthy for sensitive | Asthmatics, heart patients: short outdoor windows only | | 151–200 (red) | Unhealthy | Limit prolonged outdoor activity for everyone | | 201+ (purple/maroon) | Very unhealthy / hazardous | Stay indoors with AC | ## How weather drives vog The northeast **trade winds** blow from Hilo toward Kona about 70% of the year. When the trades are blowing, vog drifts southwest, out to sea, and doesn't affect most of the islands. When **kona winds** kick in (winter storms, summer south swells), the air pattern reverses. Vog pushes north and west, settling first on the Kona coast, then drifting up through the channels to Maui, Molokaʻi, Lānaʻi, and Oʻahu. **Vog is worst in winter (Dec–Mar)** because that's when kona winds happen most often. ## Where vog hits hardest ### 1. Big Island Kona side Kailua-Kona, Captain Cook, South Point. Especially in winter. Some days you literally can't see Mauna Loa from town. ### 2. Hilo Usually fine when trades are blowing. Can get hazy under kona winds — especially in the lower Puna district near the volcano. ### 3. South Maui Wailea, Kihei, Mākena. When kona winds carry vog up the ʻAlenuihāhā channel, south Maui gets it. ### 4. Oʻahu South shore (Waikīkī, Pearl Harbor) sees vog on the worst days, usually 24–48 hours after Big Island gets hit hard. The Koʻolau range usually blocks vog from the windward side. ### 5. Kauaʻi Furthest from Kīlauea — usually clear. Heavy kona events can occasionally reach Kauaʻi but it's rare and short. ## Health effects For most healthy visitors, vog feels like a hazy day with mild eye and throat irritation. For sensitive groups: - **Asthmatics:** Bring rescue inhaler. Vog can trigger bronchospasm. - **COPD/heart disease:** Stay indoors with AC during heavy vog days. - **Pregnant women & infants:** Limit prolonged exposure. - **Eye irritation:** Sunglasses + saline eye drops help. - **Sinus congestion:** Saline rinses; antihistamines for some. If you have a chronic condition, **talk to your doctor before traveling to Big Island.** Most people are fine. Some are not. ## Planning a trip around vog You can't predict vog weeks out, but: - **November–March:** higher vog risk → consider Kauaʻi or windward Oʻahu instead of Kona - **April–October:** trades usually win → Big Island is generally clear - **Hotel air conditioning:** filters out most particulate. Sleep with AC if you're sensitive. - **Sunsets:** vog actually makes Hawaiʻi sunsets spectacular (the particles scatter light into intense reds and oranges) ## When vog stops the activity A few things to know: - **Volcanoes National Park** sometimes closes Crater Rim Drive sections when SO₂ at the summit gets dangerous - **High-altitude hikes** (Mauna Kea summit, Mauna Loa) advise turning back during heavy vog - **Snorkel tours** typically run regardless — vog at sea level usually means slightly hazy visibility but normal water clarity - **Helicopter tours** may delay or reroute during heavy events ## Plan your Hawaii trip - **[Big Island events →](/island/big-island)** - **[Best time to visit Hawaii →](/blog/best-time-to-visit-hawaii-2026)** - **[Things to do in Kailua-Kona →](/blog/big-island-things-to-do-2026)** - **[Hawaii rainy season →](/blog/hawaii-rainy-season-2026)** > The trades take care of us 70% of the year. The other 30%, the AC takes over.