The National Weather Service has issued a dense fog advisory for the western edge of the Treasure Valley until 1 p.m. Monday, so drivers, pedestrians and cyclists all need to extra vigilant until the mist clears away.

That means it will likely take a little longer for the fog to burn away in Nampa, Caldwell, and other parts of Canyon, Gem, and Payette counties.

The fog advisory for the Boise area was lifted at 11 a.m. as visibility has improved on the eastern portion of the Treasure Valley. By 11 a.m., you could see for about 1 1/2 miles in the Boise area, according to National Weather Service reports

The reason we have so much fog is all that rain over the weekend created humid conditions Monday morning and high pressure (an inversion) is trapping that moisture near the ground.

The fog is expected to break up by early this afternoon as the day warms up and burns off the fog on the valley floor. Until then, be careful on city streets and sidewalks. Visibility is as low as 1/4 of a mile in many places across the valley other than Boise, according to National Weather Service reports.

All that moisture is also making roads and sidewalks slick, so watch your step.

The fog is also causing some flight delays at the Boise Airport, so check out flight information before heading out there.

Once the fog burns off, Monday should be a pretty nice fall day, with an estimated high temperature of 67 degrees in the Boise area with partly sunny skies.

That is expected to continue through the middle of the week, with partly sunny skies and high temperatures of 68 and 70 for Tuesday and Wednesday.

The real coup, if the weather holds up, is that Halloween should be a pretty pleasant night for trick-or-treating. The forecast calls for clouds, but it should stay dry, with a low temperature of 51 degrees.

The rain is expected to move back in by Thursday, when the Treasure Valley has a 40 percent chance of showers and an estimated high temperature of 60 degrees.