More than 20 million Americans face a severe storm threat as gulf moisture is expected to clash with a cold front ahead of the bitter cold air next week.

A moderate solar flare might affect radio communications on Earth, the National Oceanic and Atmospheric Administration said Wednesday.

Fewer states are expected to witness the northern lights on Friday night, as shown in the map above. Experts at NOAA are keeping an eye on Region 4274 as it continues to rotate to face Earth, remaining magnetically powerful and a source of strong solar flares.

Auroras could be visible — especially in darker, rural areas — in Alaska, Washington, Oregon, Idaho, Montana, Wyoming, North Dakota, South Dakota, Nebraska, Minnesota, Iowa, Michigan, Wisconsin, New York, Vermont, New Hampshire, Maine and northern parts of Illinois, Indiana, Ohio, Pennsylvania and Massachusetts.

Dust storms are sweeping across the world, harming the health of millions of people. Now, scientists are racing to keep the dirt on the ground.

The most rain fell in the North Bay and in the Santa Cruz Mountains. The weather service recorded official overall rain totals of 3.22 inches in Santa Rosa; 3.04 inches in Occidental, north of Santa Rosa; 2 inches at Ben Lomond and 1.52 inches on Mount Tamalpais.

Conditions remain quiet in the tropics, with no activity expected for the next seven days. But don't let your guard down yet.

Vietnam is rethinking how it copes with floods after a year of relentless storms has collapsed hillsides and turned streets into rivers

The Pacific Northwest will stay soggy this week as back-to-back storms will push onshore, bringing wet, windy and snowy conditions.