Portland area forecast: Clouds mix with sun as a warm day unfolds.
Tuesday brings a blend of clouds and sun, with highs flirting with 89 degrees. Monsoonal moisture from two nearby weather systems has nudged showers into parts of the region, particularly from Sweet Home northward, though much of the rain is being absorbed by a dry layer near the surface. The upshot for Portland is a slight chance of showers early in the day, with another chance by the evening commute. Cloud cover could keep temperatures down into the upper 80s, but the official high is expected near 89.
There is a 20% chance of thunderstorms in the Willamette National Forest and foothills, with the southern and central Cascades also seeing the potential for storms.
Wednesday should be partly sunny with a high near 86.
Two new low-pressure systems will bring some weak ridging to northwest Oregon and southwest Washington on Thursday and Friday. Expect a mostly sunny Thursday with temperatures around 89, followed by a largely sunny Friday with highs near 92.
The weekend forecast remains in flux, with little model agreement on Saturday. More monsoonal moisture is likely by Sunday and could trigger thunderstorms in parts of the Pacific Northwest. If you have outdoor plans for Labor Day weekend, stay tuned to updated forecasts.
Additional notes and value:
– A pattern of warm afternoons continues through the end of the workweek, with numbers peaking near the low 90s on Friday.
– The threat of thunderstorms is regional, strongest in higher elevations (Willamette NF and foothills) and in the southern/central Cascades.
– Weekend plans may be impacted by unsettled conditions and possible rain. Check forecasts closer to your plans.
Summary: A warm, mainly dry spell midweek could be interrupted by isolated showers and thunderstorms, followed by another warm period into Friday. By Sunday, unsettled monsoonal moisture may bring more widespread thunderstorm chances. Positive angle: any showers and storms could bring welcomed relief from heat and help with outdoor vegetation, but stay prepared for changes in conditions.
Helpful tip: If you’re planning outdoor activities, have a light rain jacket or umbrella handy and watch for changing storm development, especially in the mountains and forested areas.