Yesterday’s low temperature of 70 F in Yuma AZ, following a high of 101 F on 1 April, was unusually warm for early April.  It broke the daily record for 2 April which had stood since 1893.

It is not unusual for Phoenix (KPHX) to set new high minimum temperature records due to the urban heat island (UHI) effect which has increased as Phoenix has grown in size.  Here is the record report issued by NWS Phoenix this morning:

…RECORD HIGH MINIMUM TEMPERATURE TIED IN PHOENIX AND SET IN YUMA…
THE LOW TEMPERATURE YESTERDAY…2 APRIL 2011…OF 67 DEGREES IN
PHOENIX TIES THE RECORD FOR THE HIGHEST MINIMUM TEMPERATURE ON
RECORD FOR THE DATE. THE CURRENT RECORD WAS INITIALLY SET IN 2001.
THE LOW TEMPERATURE YESTERDAY…2 APRIL 2011…OF 70 DEGREES IN YUMA
SETS A NEW RECORD FOR THE HIGHEST MINIMUM TEMPERATURE ON RECORD FOR
THE DATE. THE PREVIOUS RECORD WAS 66 DEGREES SET IN 1893.
TEMPERATURE RECORDS FOR PHOENIX DATE BACK TO 1895 AND FOR YUMA BACK
TO 1878.