Heavy showers and isolated thunderstorms are expected across Hawaii’s Big Island, with locally intense rainfall possible overnight before unsettled conditions continue into Thursday.
The wettest conditions are forecast for the Hilo and Waimea areas, where skies will remain mostly cloudy and showers will become widespread at times. In Hilo, the chance of rain is put at 70% overnight, rising to 90% on Thursday as numerous morning showers give way to frequent afternoon rain. Isolated thunderstorms are also possible during the overnight period.
Forecasters say rainfall could be locally heavy during the evening. That means conditions may vary sharply over short distances, particularly around showers and thunderstorms, with some locations receiving much more rain than nearby areas. People travelling across the island should be prepared for sudden reductions in visibility and wet roads, especially during the evening and Thursday afternoon.
Different conditions from Hilo to Kona
The forecast is less consistently wet on the western side of the island. Kona is expected to turn partly cloudy overnight after evening showers and thunderstorms, with isolated showers and storms still possible after midnight. Rain chances there fall to 50% on Thursday, when the day should be partly sunny before scattered afternoon showers develop.
Kona is also forecast to be warmer, with temperatures reaching 84 to 90 degrees near the shore on Thursday. By contrast, Hilo’s daytime range is expected to be 79 to 85 degrees near the coast, while higher ground remains considerably cooler. Overnight lows in Kona are forecast at 70 to 76 degrees near the shore, compared with 68 to 75 degrees in Hilo.
| Area | Overnight outlook | Thursday outlook | Rain chance |
|---|---|---|---|
| Hilo | Showers and isolated thunderstorms | Numerous showers, becoming frequent in the afternoon | 70% overnight; 90% Thursday |
| Kona | Evening storms, then isolated showers | Isolated morning showers; scattered afternoon showers | 70% overnight; 50% Thursday |
| Waimea | Showers and isolated thunderstorms | Mostly cloudy with numerous showers | 70% overnight and Thursday |
Rain and wind risks
Waimea is also expected to remain unsettled, with numerous showers and isolated thunderstorms overnight and a 70% chance of rain. Winds there are forecast to shift from the northwest to the north-east after midnight, reaching up to 15 mph. Hilo faces winds of up to 20 mph overnight before they turn westerly, while Kona is expected to see south-easterly winds of 10 to 15 mph after an earlier southerly flow.
The wind changes are another reason for drivers and outdoor visitors to monitor local conditions rather than relying only on the general island-wide forecast. Showers may arrive with gustier conditions, and heavy rain can make exposed routes more difficult even where the broader forecast suggests only intermittent rainfall.
- Allow extra time for journeys during the evening and Thursday afternoon.
- Use greater caution on roads affected by heavy showers, particularly where visibility changes quickly.
- Check conditions before outdoor activities, especially in areas where thunderstorms are forecast.
- Keep plans flexible, as rainfall intensity may differ between nearby parts of the island.
Conditions should ease more quickly in Kona on Thursday night, when only isolated evening showers are expected and the rain chance drops to 20%. Hilo and Waimea, however, are forecast to stay mostly cloudy, with numerous showers continuing into the evening in Hilo before becoming more scattered later. Overnight temperatures will remain mild near the coast but will be much cooler at elevation, falling to around 58 to 62 degrees in higher parts of the island.
