Number of warm nights on the rise across the U.S., including Roanoke

Roanoke seeing more nights above 65 and 70 degrees

By Chris Michaels - Meteorologist

ROANOKE, Va. - The folks at Climate Central found that 87 percent of U.S. cities are seeing more unseasonably warm nights. This is also true for those of us in southwest and central Virginia, especially in Roanoke.

This is important, as it could lead to rising costs in keeping your house cool during the summer. In the southern U.S., the average cost per year to keep your house at a reasonable temperature is 450 dollars.

Part of why we see warmer nights is the increase in humidity. 

When dew points are higher, the air has more moisture and temperatures can't drop very much. When dew points are lower, the air has less moisture and temperatures can drop more.

This year alone, Roanoke has seen 42 nights in which the low temperature was 65 degrees or warmer. That's the most through July 12 on record.

We've also seen the second most nights of 70 degrees or warmer through this date.

This kind of nighttime warmth is enhanced when you're in the city. Cities retain more heat, because surfaces like buildings, asphalt and concrete absorb heat more efficiently. In rural areas, like where official temperatures are recorded, heat is released more efficiently at night. 

This is why you'll notice, shortly after sunset, that the temperature can be a few degrees warmer in the City of Roanoke than maybe in parts of the county where there's less infrastructure.

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