Portland area temperatures are expected to climb into the 80s on Tuesday, May 12, 2026, before storms begin building over the Cascades after sunset and send scattered thunderstorm activity toward the region Tuesday night.
A mix of sun and clouds should help warm the Willamette Valley back into the 80s during the day, but skies are expected to turn mostly cloudy by evening. Thunderstorms are not expected to become severe, though some isolated areas could see heavy rain, small hail and lightning, with the main impacts staying east of the Portland metro area.
For Portland, the day marks the peak of this week’s heat. It also starts a stretch of wetter, cooler weather that will push temperatures down and bring a sharper change in the forecast by midweek. After a dry stretch earlier in the day, scattered rain showers and cooler temperatures are expected Wednesday, and conditions should begin drying out some by Wednesday afternoon.
Rain is expected to keep falling on and off across the Portland area from Tuesday night through Friday night, adding up to nearly a half inch. The cooling trend will deepen as the week goes on, and by Saturday highs are expected to settle into the low to mid 60s, well below average for this time of year.
The changes will be even more dramatic in the mountains. Nearly a foot of new snow is possible for the highest point of Mt. Hood, and snowflakes could fall as low as 4,500 feet as moisture and colder air move back in. That shift points to a wetter, more unsettled pattern across the region even as the lower elevations see rain rather than snow.
Drier skies and warmer temperatures are expected by the end of the weekend, and highs should return to above-average conditions early next week. For now, the pattern is moving from Tuesday’s warmth to a colder, wetter stretch that will be most noticeable east of Portland and in the higher terrain before the region turns back toward milder weather.
