San Diego experienced the warmest October on record with an average monthly temperature of 74.4 degrees. That's 7.7 degrees above average, says the National Weather Service .

The balmy reading at San Diego's Lindbergh Field broke the previous October average of 72.2, set in 1983. The third warmest October -- 71.8 -- occurred last fall.

Forecasters say the warm weather was heavily influenced by the ocean, which has been unusually warm for most of the past year. Warm water moderates air temperatures. Sea surface temperatures were 70 or above along the entire coast in October. The seasonal average is 64-65 degrees.

Sea surface temperatures have not cooled off with the start of fall. Image taken Sunday at La Jolla Cove. — John Gastaldo

Scientists say the warmth of the ocean could be tied to both a period long-term warming of the Pacific and the El Nino that developed earlier this year.

The weather is expected to sharply change late Monday when a weak storm tracks through San Diego County. About one-quarter of an inch of rain is expected along the coast.

October recap:

There were seven days in which the temperature was 10 or more degrees above normal in San Diego. There was only one day in which the temperature was below normal. The airport recorded 0.43'' of rain, which was 0.14'' below normal.

Ocean temps, Sunday, Nov. 1

San Diego Bay: 73

Scripps Pier: 71

Offshore:

Station 46086 (27 miles southeast of San Clemente Island): 73.9

Comparisons:

Miami: 81.5

Boston: 53.4

Bar Harbor, Maine: 51.4

Ocean City, Maryland: 61.5