Thunderstorms for some Saturday, cooler Father's Day for Portland area

The threat of thunderstorms, heavy rain and cooler temperatures returns in Portland's late spring storm threat.

PORTLAND, Ore. (KOIN) -- The threat of thunderstorms, heavy rain and cooler temperatures returns in Portland's late spring storm threat.

Saturday will likely be the rainiest day of the weekend and the coolest. Mostly cloudy skies will drop temperatures to the mid-60s during the afternoon. Isolated thunderstorms are likely for much of Washington, but northwest Oregon could see a few stray storms as well. No severe weather is expected, but small hail and lightning are the biggest threats to outdoor activities this weekend.

Lingering rain showers will remain Father's Day. Nearly 10-degree cooler-than-average temperatures will stay on Sunday. Temperatures will sit in the mid to upper 60s for the Willamette Valley. This comes as rain accumulation nears a quarter to a half inch of rain from Saturday to Monday afternoon.

The chance to see rain return to the region will help clear high pollen counts and put the fire threat off a bit longer.

The late spring storms are short-lived. Summer heat builds just in time for the start of the new season on Thursday. Summer will bring the heat with Portland's temperatures climbing into the mid-80s.