Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
316 AM EDT Sun Oct 19 2025

Valid 00Z Mon 20 Oct 2025 - 00Z Mon 27 Oct 2025

The main surface high will be situated well to the northeast of 
Hawaii early this week, with the typical easterly trade wind 
pattern over the Islands through the majority of the forecast
period. The ensemble means are hinting at a weak inverted surface
trough developing over the state Wednesday into Thursday in 
response to a broad upper trough over the region. The surface high
then rebuilds closer to the Islands to close out the week.

Normal coverage of showers across the windward terrain can be
expected on most days. It currently does not appear that the mid-
week trough will be strong enough to advect deeper moisture from
the ITCZ, so therefore no major rainfall events are anticipated
based on the latest model guidance.

Hamrick