The calendar may say that it is Fall, but it sure felt like Summer around the Bay Area Monday and Tuesday(October 1st/2nd) as afternoon temperatures soared into the triple digits. High pressure aloft, very warm air mass aloft and offshore flow (NE and E winds) led to the record warmth. The warmest conditions were observed across the interior valleys. However, well above normal readings were also observed the coast. In fact, downtown San Francisco recorded a high temperature of 94 degrees on Tuesday. The Bay Area experiencing late season heat is not all that uncommon. The record books indicate the one year ago hot temperatures were unseasonably warm in late October. One more interesting fact is that in 1980 a major heat event occurred setting record maximum temperatures at all notable climate stations on October 2nd.

Below are two RERs issued for Record Temperatures
 

RECORD EVENT REPORT 
 NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
 530 PM PDT MON OCT 1 2012
 
 ...RECORD HIGH TEMPERATURE IN KENTFIELD CA...
 
 A RECORD HIGH TEMPERATURE OF 97 DEGREES WAS SET AT THE CLIMATE SITE 
 IN KENTFIELD CA TODAY. THIS BREAK THE OLD RECORD FOR THIS DATE OF 96 
 SET IN 1913.

RECORD EVENT REPORT
 NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
 515 PM PDT TUESDAY OCT 02 2012
 
 ...RECORD HIGH TEMPERATURES TODAY...
 
 RECORDS SET...
 
 LOCATION                NEW RECORD   OLD RECORD AND YEAR 
 --------------------------------------------------------
 KENTFIELD                 99           98         1980
 MOUNTAIN VIEW             95           94         1980
 SAN JOSE                  96(TIED)     96         1980
 KING CITY                108          107         1980