Cloudiest Cities in America

by Liz Osborn © Current Results Nexus

Heavy Cloud

Portland, Oregon and Cleveland, Ohio top the list of cloudiest cities in the United States. If measured by the number of heavily overcast days each year, the days when more than three-quarters of the sky is covered in cloud, then Portland comes in first, averaging 222 cloudy days annually, followed by Cleveland at 202 days. Portland and Cleveland, along with Seattle, Columbus and Detroit, have heavy cloud cover on over half of all days.

Overall, 17 major American cities are mostly cloudy for more than 150 days a year. The cities with frequent cloudy weather are not concentrated in any one particular region, but are scattered throughout the country, from Michigan to Texas and from Washington to North Carolina.

The major cities included in these weather rankings are all the cities in the USA with over 440,000 people on July 1, 2006, according to the US Census Bureau's estimates. Of these, 37 cities collect weather data on the amount of cloud cover each day.

Most Cloudy Days

Days of partial cloud are more common in Cleveland than Portland, the country's two cloudiest big cities. Partial cloud is defined as cloud covering from over one-quarter to as much as three-quarters of the sky.

When days with partial cloud are added to the days of heavy cloud, to include every day that cloud covers more than one-quarter of the sky, then Cleveland's average of 299 days a year edges out Portland's 296 days. From this perspective, Cleveland is the cloudiest American city, rather than Portland.

Seattle, Columbus and Detroit join Cleveland and Portland as the major US cities that have some cloud on at least three out of four days. All five cities average 290 days or more a year when cloud covers over one-quarter of the sky. Another 15 cities are cloudy on at least 250 days a year.

Partial Cloud

Ten of America's major cities average over 110 days a year of partially cloudy weather. These are days when cloud covers between one-quarter and three-quarters of the sky.

Except for Philadelphia and Houston, these partially cloudy cities don't get enough days of heavy overcast, when cloud covers more than three-quarters of the sky, to rank among the cloudiest cities in the United States.