Portland could get a very typical spring day Wednesday as a shallower marine layer keeps clouds mostly at bay, allowing for more sunny skies.
The National Weather Service says high clouds along the Cascades may venture into the valleys later in the day. But Portland should be mostly clear, and the high temperature will reach near 75 degrees, which is about average for late May.
Thunderstorm chances increase on Thursday and Friday afternoon. The best chance of thunderstorms is along the Cascades with a 15-25% probability. Take note of that if you’re planning a hike in the mountains later this week. The Willamette Valley has a 10-15% chance of thunder both afternoons. Chances are greater Thursday as there may be more moisture in the upper atmosphere.
Other than a thunderstorm chance, Portland’s weather should be pleasant and mostly sunny Thursday, with a high near 83 degrees.
Friday will likely be the warmest day this week even with a slight chance of showers and thunderstorms in the forecast. Skies will be sunny during the bulk of the day. The high will reach near 85 degrees.
Current long-range forecasts are showing temperatures cooling quickly back down to normal by Saturday. Highs over the long weekend will be in the 70s in the valleys under partly cloudy skies and 60s along the coast and in the mountains.