News Made Clear · Loading…
An extensive layer of low cloud and fog covered western parts of the US states of Washington and Oregon on 19 September. NASA satellites also showed how much of it disappeared later that day.
AI translation of the original article. Independent human translation review is pending. Read the original
Review information is loading.
The MODIS instrument on NASA’s Terra satellite captured the cloud cover on 19 September 2026 at around 10.45 local time. The low stratus clouds and fog extended from the coast to the western foothills of the Cascade Range. Higher parts of the Olympic Mountains in Washington and the Oregon Coast Range rose above the cloud layer. [1]
According to NASA, the image also shows extensive cloud cover over the Pacific Ocean. Smoke from wildfires was also present in the valleys of the North Cascades. The source does not name individual fires. [1]
The clouds were associated with an influx of cool, moist sea air. According to NASA, citing the US National Weather Service, this air flowed inland from the ocean over several consecutive nights. Early on 19 September, the influx was particularly strong, causing the cloud cover to extend far inland.
NASA explains that such low clouds form when moist air near the surface is trapped beneath a warmer layer of air: a temperature inversion. If the lower layer of air cools sufficiently, the water vapour condenses. Where the clouds reach the ground, there is fog. [1]
When NASA’s Aqua satellite passed overhead at around 16.15 local time, skies had cleared over much of the area. Some marine cloud still lingered along the Oregon coast. Temperatures there remained lower than inland; NASA gives no difference in degrees. [1]
1 listed sources · explore evidence, limitations and provenance.
Sign in to give this article a thumbs up or down.
Private test discussion. Comments are readers’ views and are not yet automatically fact-checked. Editing is available for 60 seconds after posting.
Sign in with a confirmed reader account and choose a username to read comments and participate.
Sorting applies to top-level comments; replies remain oldest first. New comments and likes can change the order. Refresh for the current ranking.
Loading comments…