On Oct. 20, the national high and low temperatures were at Ocotillo Wells, Calif., and Alamosa, Colo., 642 miles apart. Is there any record of the shortest distance between two locations featuring the daily national high and low temperatures?
— Larry Maday
Because temperatures usually decline by 5.4 degrees per 1,000 feet of vertical ascent, elevation is the key to an answer to your question. Locations near each other but at greatly different elevations are likely candidates, and documentation of the nation’s daily temperature extremes since 1995 bears that out. The results indicate that Truckee (elevation 5,840 feet) and Death Valley (190 feet below sea level), both in California and 264 miles apart, occasionally register the nation’s lowest and highest temperatures, respectively, on the same day.