Forecast confidence is extremely low at this point, but we plan to publish a cloud forecast every other day leading up to the total solar eclipse on Aug. 21. We can begin to assemble some likelihoods from very generalized upper-air and precipitation patterns. Our confidence will get higher as we approach the big event.
Good news! We’re now within 15 days of the solar eclipse, which is in range of some better forecast models.
Forecast notes as of Aug. 7, 2017:
Forecast confidence: Very low
- Early fog on the West Coast could limit visibility, depending on how fast it burns off.
- A midday weather system could be a problem for parts of the Midwest and Plains.
- There’s a high chance of typical afternoon thunderstorms in the Southeast. Unfortunately, we’re not going to know where these will pop up, even the morning of the eclipse.
Average weather conditions for Aug. 21
The timing of the eclipse is ideal, at least for the West. It begins just before 11 a.m. local time on the West Coast, which is usually enough time to burn off the fog that can often occur out there.
The intermountain areas typically see thunderstorms bubble up in the afternoons during this time of year. These are associated with the Southwest monsoon, a period of increased thunderstorms and rain during the late summer and early fall. But the eclipse passes through this region around noon, so it should beat the worst of that threat.
Clouds often pop up along the rest of the path throughout the day simply because of warmth and moisture. Those two things combined lead to rising air, which creates clouds. So the cloud risk gets greater the farther east you go. On top of that, South Carolina will see totality the latest in the day — after 2:30 p.m.
Obviously the eclipse is still too far away to get a good forecast. But some of the forecast models we use to predict the weather go out several weeks, and at this point, they cover the day of the eclipse.