Puna Weather
Tuesday 10th March 2026
Today light southeast winds with only a few brief showers most areas.
Wednesday and Thursday moderate to breezy southerly winds with occasional heavy rain and thunderstorms. Some of the thunderstorms could be strong.
Friday and Saturday very windy, especially for south facing slopes. Occasional thunderstorms accompanied by strong winds, frequent lightning, and hail.
Monday through Wednesday light winds with occasional heavy rain. VOG and afternoon thunder are possible.
A large trough to our northwest (satellite loop) will move closer to our island over the next couple of days. Currently the trough is pulling deep moist air from the tropics over Kauai. As the trough gets closer, that moisture will move over us too. The trough also moves cold air aloft over us which brings the risk of thunderstorms and mountain snows.
Even with the massive trough in the central Pacific the surface high pressure remains anchored in the eastern Pacific through the upcoming weekend. The pressure gradient between these two will accelerate southerly winds over our island, especially late Friday and Saturday (surface chart). The GFS shows 12 to 24 hours of 40mph south winds and the European models showing 50mph. This southerly flow will support heavy rains which could be persistent along south facing slopes. The southerly direction only supports widely scattered activity elsewhere.
Thunderstorms are possible beginning Wednesday with models showing the strongest instability overhead late Wednesday through early Saturday. CAPE values rise into the 1500-2000 J/kg range which supports widely scattered strong thunderstorms and isolated severe ones.
At this point it looks like the more sustained rains will be over Kauai and Oahu, with more spotty rainfall over us. Nonetheless we will still see strong thunderstorms and heavy rain.
The winds die down around Monday, but the moisture remains through at least the middle of next week.
If Kilauea erupts before Sunday ash is mostly pushed towards Waimea. After Sunday it is mostly pushed towards Hilo.
Hail threat:
For hail to reach the ground in the tropics, the "hail growth zone" (typically between 10F and -20F) needs to be low enough that the stones don't completely melt during their 11,000' descent through the warm lower atmosphere. If a strong updraft CAPE > 2000 J/kg can sustain stones to a significant size, they have a high probability of surviving the trip to the surface. Hail in Hawaii usually requires organized convection (multicells or supercells) rather than simple pulse storms. Models are showing 0–3km SRH (Storm Relative Helicity) values spiking near on Friday night. In the presence of a low-level jet, this is sufficient for storm rotation. Rotating updrafts are more efficient at "recycling" hail embryos through the growth zone multiple times. This is the classic mechanism for the rare "record hail" events seen during previous Kona Lows (like the 2012 event).
