This will act as a printing error. But temperatures in Campo – a desert community 41 miles southeast of San Diego – dropped to 29 degrees just before dawn Sunday. The average low temperature before dawn at this time of year is around 55 degrees.
The reading “not only breaks a daily record, but binds their record for the month of June back in 1977!”, The National Weather Service said in a statement on Twitter.
Forecaster Brian Adams tied it to radiation cooling, the process by which the earth radiates heat during the night. This phenomenon can lead to incredible temperature drops if the sky is clear, the wind is light, and the air is dry. All three of these conditions occurred on Sunday.