Big Island Weather Aug 24: The Must-See Forecast Before You Go
Big Island Weather Forecast: Your Simple Guide for Tonight Through Monday Night
Quick Summary: A tropical storm named Moke is passing far south of Hawaii. It’s bringing lots of rain, strong winds, and rough seas to the Big Island—especially on the windward (eastern) sides. Things calm down by Tuesday!
What’s Happening? (The Big Picture)
Imagine a big spinning storm (Tropical Storm Moke) swirling about 300 miles south of Kailua-Kona. Even though it’s far away, it’s pushing moisture and strong winds toward the Big Island.
Key things to know:
- Heavy rain on windward (east) slopes → Flash Flood Watch until Monday afternoon
- Strong, gusty winds (up to 50 mph in spots) → Wind Advisory until midnight
- Rough seas for all Hawaiian waters → Small Craft Advisory until 6 AM Monday
- Improving Tuesday: Drier, calmer, typical trade-wind weather returns
IMPORTANT ALERTS
- Flood Watch – Big Island (until Monday afternoon)
- Wind Advisory – Many Big Island & Maui areas (until midnight tonight)
- Small Craft Advisory – All Hawaiian waters (until 6 AM Monday)
- Tropical Storm Warning – Offshore waters only
Regional Forecasts (Tonight → Monday → Monday Night)
Hilo & Puna (Windward Side – Wettest!)
These two areas share nearly identical forecasts.
| Time | Conditions | Temperatures | Winds | Rain Chance |
|---|---|---|---|---|
| Rest of Tonight | Showers | 70–76°F (shore) / 63°F (4000 ft) | West ≤10 mph | ~100% |
| Monday | Morning showers → afternoon numerous showers | 81–87°F (shore) / 69°F (4000 ft) | East ≤15 mph, increasing afternoon | ~100% |
| Monday Night | Mostly cloudy, scattered showers | 67–75°F (shore) / 60°F (4000 ft) | NE ≤10 mph | 50% |
ELI5: Think of a garden hose spraying the east side of the island all night and day. Bring a rain jacket and umbrella!
Kona (Leeward Side – Drier, But Still Showers)
| Time | Conditions | Temperatures | Winds | Rain Chance |
|---|---|---|---|---|
| Rest of Tonight | Partly cloudy → isolated showers after midnight | 71–77°F (shore) / 61°F (5000 ft) | Light | 50% |
| Monday | Morning: mostly sunny, isolated showers → Afternoon: mostly cloudy, numerous showers | ~89°F (shore) / 73°F (5000 ft) | Light | 70% |
| Monday Night | Evening: scattered showers → After midnight: isolated showers | 74–79°F (shore) / 53–59°F (5000 ft) | Light | 50% |
ELI5: Kona gets a break in the morning, but afternoon clouds and showers roll in like clockwork.
Waimea & Kohala (Breezy & Wet)
These two areas have the same forecast.
| Time | Conditions | Temperatures | Winds | Rain Chance |
|---|---|---|---|---|
| Rest of Tonight | Showers early → numerous showers after midnight | 70–76°F (shore) / 64–70°F (3000 ft) | East up to 25 mph (Breezy!) | 90% |
| Monday | Morning: numerous showers → Afternoon: scattered showers | ~83°F (shore) / 72–82°F (3000 ft) | East up to 25 mph | 70% |
| Monday Night | Scattered showers, becoming partly cloudy | 66–75°F (shore) / 59–65°F (3000 ft) | East up to 20 mph | 40% |
ELI5: Windy! Hold onto your hat. Rain comes in waves—heavy at night, lighter by Monday afternoon.
South Big Island (Kaʻū – Windiest!)
| Time | Conditions | Temperatures | Winds | Rain Chance |
|---|---|---|---|---|
| Rest of Tonight | Windy + Showers | ~78°F (shore) / 63°F (5000 ft) | East 10–30 mph, gusts to 50 mph | ~100% |
| Monday | Windy, partly sunny, scattered showers | ~88°F (shore) / 72°F (5000 ft) | East 10–30 mph | 50% |
| Monday Night | Partly cloudy, breezy, scattered → isolated showers | ~75°F (shore) / 56°F (5000 ft) | NE up to 25 mph | 40% |
HEADS UP: Gusts to 50 mph tonight! Secure loose items, avoid high-profile vehicles on exposed roads.
Waikoloa (Kohala Coast – Resort Area)
| Time | Conditions | Temperatures | Winds | Rain Chance |
|---|---|---|---|---|
| Rest of Tonight | Partly cloudy, breezy, scattered → isolated showers | 73–78°F (shore) / 62°F (4000+ ft) | East up to 20 mph | 50% |
| Monday | Partly sunny, scattered showers | 86–92°F (shore) / 69–76°F (4000+ ft) | North up to 15 mph | 50% |
| Monday Night | Breezy, evening scattered → overnight isolated showers | ~77°F (shore) / 54–61°F (4000+ ft) | East up to 20 mph | 40% |
ELI5: Warmest daytime highs on the island (low 90s!). Breezy nights, scattered showers—typical "resort weather" with a tropical twist.
For Pilots & Boaters (Simplified)
Aviation
- Windward Big Island: Low clouds & rain → MVFR/IFR conditions (poor visibility, low ceilings) through tonight
- Rest of state: Mostly VFR (good flying weather), but windward mountains may have MVFR periods
- Turbulence alert (AIRMET Tango): Low-level turbulence downwind of terrain
- Mountain obscuration alert (AIRMET Sierra): Clouds hiding mountain tops
- Tropical Storm Moke tracked under TC SIGMET XRAY
Marine
- All waters: Fresh to strong winds, rough seas through tonight
- Small Craft Advisory until 6 AM Monday
- Tropical Storm Warning for offshore waters only (not coastal)
- Surf: East-facing shores choppy & elevated; south shores slightly below summer normal but a new south swell arrives Mon–Tue; west/north swells from Hurricane Lala fading
ELI5 for boaters: Stay in port if you’re on a small boat. Big waves, strong winds, and storm energy in the water.
Fire Weather
- Good news: Humidity is higher than normal (moist air from Moke)
- Heavy rain on windward/southeast Big Island → low fire danger there
- Trade winds strong but easing by Monday night
- Typical summer pattern returns Tuesday → fire risk back to normal
Your Action Checklist
- Check alerts before traveling – Flood Watch, Wind Advisory, Small Craft Advisory active
- Secure outdoor items – especially in South Big Island, Waimea, Kohala (gusts to 50 mph!)
- Avoid flooded roads – "Turn around, don’t drown" – flash flooding possible on windward slopes
- Pack rain gear if heading to Hilo, Puna, Waimea, Kohala, South Big Island
- Plan indoor activities for Monday afternoon (showers likely island-wide)
- Boaters: Stay ashore until Small Craft Advisory lifts (6 AM Monday)
- Drivers: High-profile vehicles use caution on exposed roads (Saddle Road, Kohala Mountain Road)
- Tuesday onward: Enjoy improving weather!
Summary
| What | When | Where | Impact |
|---|---|---|---|
| Heavy Rain / Flood Risk | Tonight → Mon afternoon | Windward & SE Big Island (Hilo, Puna, Waimea, Kohala, Kaʻū) | Flash flooding possible |
| Strong/Gusty Winds | Tonight (until midnight) | South Big Island, Waimea, Kohala, Maui County | Gusts to 50 mph, Wind Advisory |
| Rough Seas | Tonight → 6 AM Mon | All Hawaiian waters | Small Craft Advisory |
| Improving Weather | Tuesday + | Statewide | Drier, moderate trades, typical summer pattern |
Bottom line: Wet, windy night and Monday—especially on the east/south sides. Tuesday brings relief!
FAQ
1. Is Tropical Storm Moke going to hit the Big Island?
No. Moke is passing ~300 miles south of the island. We’re only getting the outer moisture and wind effects—not the storm itself.
2. Why is Hilo so much wetter than Kona?
Trade winds blow from the northeast. They push moist air up the east-facing slopes (windward), where it cools and drops rain. Kona sits in the "rain shadow" on the leeward side, so it stays drier.
3. What does "MVFR/IFR" mean for aviation?
- VFR = Visual Flight Rules (clear enough to fly by sight)
- MVFR = Marginal VFR (lower clouds/visibility, caution needed)
- IFR = Instrument Flight Rules (poor visibility, must fly by instruments)
Windward Big Island has MVFR/IFR tonight due to rain and low clouds.
4. When will the wind die down?
Winds ease Monday night as Moke moves west and the pressure gradient relaxes. By Tuesday, trades drop to moderate strength—much more comfortable!
5. Should I cancel my helicopter tour or boat trip?
- Helicopter tours: May be delayed or rerouted due to low clouds/rain on windward side. Call your tour operator.
- Boat trips: Small Craft Advisory until 6 AM Monday. Most morning tours likely canceled. Afternoon Monday may run if conditions improve—check with the captain.
Data Source: NOAA / National Weather Service Honolulu
Sponsored by: Blue Hawaiian Helicopters – Big Island Helicopter Tours
Stay safe, stay dry, and aloha!