Last night here in San Diego, the temperature rose overnightf rom 71 at 1:00 AM to 75 at 2:45 AM. Even more dramatically, about 3 weeks ago it rose from 79 at half-past midnight to 87 at 3:45. In both cases, the air pressure was stable and the winds were either non-existent or mostly so with brief periods of a very mild breeze. Last night, the relative humidity dropped from 73% to 35% during the hours in question; three weeks ago, from 60% to 30%.
So … what could be causing the temperature to rise in the absence of sunshine? Is it related to the humidity?