Tomorrow's Weather Forecast - Portland

Tomorrow's weather in Portland. high 20°C (68°F), low 12°C (54°F). Rainy.

Tomorrow’s Outlook

Tomorrow brings a similar temperature to today. Expect heavy rain in the evening, with rain chances climbing as high as 84%. That risk lines up with humidity averaging 77% through the day the more moisture in the air, the more readily clouds build into showers. Humidity holds around 77%, giving the air a damp, heavy feel even without much heat behind it. A light breeze near 24 km/h is expected. Sunrise is at 6:45 AM and sunset at 7:27 PM, for about 12h 41m of daylight.

Tomorrow
20°/ 12°
Today20° / 11°

Tomorrow’s Hourly Weather Outlook

Morning6 AM – Noon14°
Rain probability
1%
Wind speed
12 km/h
AfternoonNoon – 6 PM19°
Rain probability
33%
Wind speed
24 km/h
Evening6 PM – Midn14°
Rain probability
84%
Wind speed
15 km/h
NightMidn – 6 AM13°
Rain probability
1%
Wind speed
9 km/h

24-Hour Rain & Temperature Forecast

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Temperature · peaks at +20°C

Planning Advice for Tomorrow

Clothing
Waterproof jacket and umbrella strongly recommended.
Outdoor
Not ideal for outdoor plans or car washes — heavy rain expected.
Travel
Expect traffic slowdowns from wet roads. Allow extra time.

Sunrise & Sunset

Sunrise
Dawn 6:15 AM
Total Daylight
Full day forecastSolar noon 1:06 PM
Sunset
Dusk 7:57 PM
vs today-4 min daylight
Sunrise shift1 min later
Sunset shift2 min earlier

5-Day Weather Forecast

Full 15-Day Forecast

Weather Insight

Portland is forecast to reach a high of 20°C tomorrow, with an overnight low around 12°C. That's 5° below the long-term average high of 25°C for this time of year. It continues a recent pattern — 4 of the last 28 days with published data have run cooler than normal. Expect a high chance of rain (84% probability) and moderate breezes averaging 24 km/h. Air quality is currently Moderate (AQI 52), driven mainly by PM2.5 at 8.6 μg/m³.

Today vs Normal

20°C-5° below normal

The long-term average high for today is 25°C.

4 of the last 28 days with published data ran above normal.

It continues that pattern - today's forecast is also running below normal.

2026-08-28: 23°C23°2026-08-29: 19°C19°2026-08-30: 21°C21°2026-08-31: 29°C29°2026-09-01: 20°C20°2026-09-02: 14°C14°2026-09-03: 18°C18°2026-09-04: 17°C17°2026-09-05: 19°C19°2026-09-06: 15°C15°2026-09-07: 20°C20°2026-09-08: 25°C25°

Red = above normal, blue = at or below · last 12 days

Air Quality

Air Quality
Moderate

Air quality is acceptable for most people. Unusually sensitive individuals should consider reducing prolonged or heavy outdoor exertion.