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From left, Bryce Williams, 10, Reece Williams, 6, and their mother Jennifer Williams, of San Ramon, play with their dog Molly at the dog park in Dublin, Calif., on Tuesday, Jan. 14, 2014. Dublin hit a high temperature of 72 degrees and the forecast for the rest of the week calls for temperatures in the 70s. (Doug Duran/Bay Area News Group)

OAKLAND -- It's January -- someone should let Mother Nature know. The clock had not yet struck noon Tuesday and already record-high temperatures in Oakland were broken for the second day in a row, prompting rare winter fire warnings for East Bay hillsides.

"When you are breaking record-highs in the morning by four degrees, it's not your normal day," in January, National Weather Service Meteorologist Ryan Walbrun said.

A month after a cold snap that broke record lows locally, highs hit 73 in Oakland on Tuesday, the hottest Jan. 14 on record since meteorologists began collecting data in 1948. Temperatures also reached the 70s in other South Bay and East Bay cities, and 72 at San Francisco International Airport.

So far this month, record-high temperatures have been broken in Richmond, San Rafael, Salinas, at Moffett Field and at SFO, according to data from the weather service.

A combination of heat, low humidity and gusty winds on the heels of the driest year on record for nearly every major city in California, prompted the weather service to issue a red-flag fire warning for the North Bay and East Bay hills effective until 10 a.m. Thursday.

Such a warning is rare for January, and employees at the National Weather Service could not recall it happening before, except possibly during California's dry spell in 1976-77.

Berkeley fire crews were treating Tuesday as if it were the middle of the fire season, which officially begins in June and ends in November. Police officers patrolled the hills to ensure roads were accessible; firefighters carried extra equipment; and fire crews prepared to send first-alarm responses to any reports of smoke in the hills, though none came by afternoon, said Berkeley Fire Deputy Chief Avery Webb, a 30-year department veteran.

"We had an early start to the season, and here we are in January, and there's no end in sight," Webb said.

Further south, Santa Cruz County fire officials warned that warm and dry conditions continue to pose a wildfire threat.

"We might be in January, but we're still in a burn period," said Cal Fire Capt. David Hibdon, in the Felton command center. "We could still have a very devastating fire."

Santa Cruz County's coast reached 78 degrees with 17 percent humidity on Tuesday, Cal Fire reported. Low winds, which on Tuesday were at 5 mph, kept officials from issuing the red flag alert, but Hibdon said outdoor brush burning is banned.

A grass fire on Kimball Island in the Sacramento-San Joaquin Delta sent giant plumes of black smoke in the air above Antioch and led to evacuations on the island. The blaze started in the brush and tules on the southern part of the island about 3 p.m., and later spread to dwellings farther west.

In Clayton, where a massive fire caused by target shooting scorched 3,100 acres on Mount Diablo, residents remained vigilant and ready to evacuate if a fire breaks out. Elaine Baker of Concord, who is a member of the Contra Costa County Animal Rescue Team that evacuates horses from the hills in times of danger, said she's always watching the mountain, "keeping an eye, ear and nose out for signs of fire."

"We've had some wake-up calls," she said, referring to the fire on Mount Diablo and other fires. "I don't think a lot of people realized the danger is there. It's always there."

Meanwhile, in Southern California, numerous firefighters were dispatched to attack small but potentially dangerous blazes Tuesday as gusty Santa Ana winds swept the region and humidity levels plunged to vegetation-withering, single-digit levels.

Fire warnings aside, some took advantage of the unseasonably sunny day to enjoy the outdoors, though they were aware the lack of rain has a cost.

Ann Bernal of San Jose joined dozens of people enjoying the day at Campbell Park in Campbell but said she expects to see water restrictions in the coming months. "I'm very concerned," she said. "It's looking like it's going to be a very dry year. ... It's just weird season. With everything going on in the East Coast and the weather being so extreme on both ends. It's unnerving."

Staff writers Mark Gomez, Paul Burgarino and Eric Kurhi, The Associated Press and the Santa Cruz Sentinel contributed to this report. David DeBolt covers breaking news. Contact him in Richmond at 510-262-2728. Follow him at Twitter.com/daviddebolt.