Marine Weather and Tide Forecast for Harbor, OR

MARINE
Updated 630 PM PDT Monday, May 4, 2026...Light south winds and fog are expected tonight, with gradually diminishing seas.
An extended period of relatively calm conditions will continue into Wednesday, with west-northwest swell dominated seas likely remaining below 10 ft through Friday. Moderate north winds likely develop on Friday evening, with the return of the thermal trough. North winds then increase during the weekend with steep seas possible.

PREV DISCUSSION
/Issued 155 PM PDT Mon May 4 2026/

DISCUSSION...

Marine stratus still covers much of the coast and Umpqua Basin this afternoon. We're also watching some cumulus build ups along the Cascades as the atmosphere begins to destabilize. The Cascades and most of northern California will be areas to watch for thunderstorms this afternoon. Convective available potential energy(CAPE) is modest around 500-750 J/kg, which is enough to support some stronger storms for our area. Upper level shear is also about 20 to 30 knots out of the east. Main threats will be some gusty winds and sporadic lightning through this afternoon and early evening.

Thunderstorm activity will diminish tonight as the atmosphere begins to stabilize. There could be some patchy fog along the coast tonight and perhaps in some of the smaller river valleys.
The GFS and NAM are both showing some light QPF along the coast, and that usually suggests some drizzle mixed with fog in the marine layer. In any case, just something to watch out for tonight.

The upper level low bringing all these thunderstorms will move eastwards through the day on Tuesday into southern California as high pressure begins to build over our region. The net effect will be warming temperatures above normal for this time of year as highs push into the lower 80's here in Medford on Tuesday and mid to 80's through the rest of the week. Looking at Medford's climate data, we'll be about 15 degrees warmer than the normal highs for this time of year.

Towards Thursday, models are showing a short wave riding over the top of this ridge in Washington. 850mb equivalent potential temperature maps are showing a dry cold front approach our area around early Thursday, yet it never really moves through according to the GFS. With that said, our official forecast trends down from 85 degrees to the upper 70's on Friday, perhaps due to cloud cover and the breaking down of the ridge. Our best chance at more precipitation is towards Friday evening when the PoP is around 5-10% in our Oregon areas. Essentially, it's looking pretty dry and warm through the week.

MFR WATCHES/WARNINGS/ADVISORIES
OR...None.

CA...None.

PACIFIC COASTAL WATERS...None.