Posted on Mon, Jun. 29, 2009

Thermal lag >

Why isn't the first day of summer the hottest day of the year? The sun is at its most overhead position and we have the most sunlight that day, too.

—Julia

You can attribute this to "thermal lag." The temperature doesn't warm up instantly. It's analogous to a pot of water on a stove, which doesn't start boiling immediately. Same is true for our summer season. The warmest days of the year here in Wichita typically aren't in June but in late July and into August. We see thermal lag on a daily basis, too: Noon isn't the hottest part of the day; mid- to late afternoon is.

Send your weather questions to "Ask Storm Team 12," KWCH-TV, P.O. Box 12, Wichita, KS 67201, or e-mail to askstormteam12@kwch.com.