Hillsboro fog forecast

Tomorrow the chance of fog at Hillsboro is 15%: fog unlikely. That is the chance that visibility drops to a mile or less at some point that day. It is a chance, not a promise, and it can change as new forecasts arrive (this one was updated Thu, Oct 8, 7:25 PM PDT).

Tonight the chance of fog at Hillsboro is 0% (fog unlikely). That covers the rest of the day in local time, from now until midnight.

Fog on land usually thins within a few hours after sunrise as the sun warms the ground, and is often gone by late morning, though it can last longer under thick low cloud or in sheltered valleys. Airport reports show fog most often between 3 and 6 AM local time. Exact fog start and clearing times, hour by hour, are part of the full forecast in 4070 Pro.

Hillsboro sits in a valley. On calm, clear nights cool air drains into valleys and settles there, and when it cools to its dew point the moisture condenses into fog that is usually thickest around sunrise. In the last two years of airport weather reports here, fog (visibility of a mile or less) was reported in about 4.2% of hours. It showed up most often in January, and most often between 3 and 6 AM local time.

Fog is hard to forecast. The first several hours are the most reliable. Further out the forecast leans on how often fog happens at Hillsboro at that time of year, so read the second and third day as a chance, not a prediction. The chance combines several weather models with the place's own fog history and is updated every hour.