Las Vegas will hit about 102°F Tuesday before afternoon thunderstorms bring lightning, brief rain and gusty winds. A short midweek cooldown arrives before another heat rebound.

Honolulu stays warm and breezy Tuesday, but coastal flooding and stronger winds will complicate shoreline plans through Wednesday. Showers become more widespread heading into the weekend.

Forecasters give one system a 90 percent formation chance within a week, with dangerous surf possible even without a direct hit.