SAN JOSE -- It was another balmy, breezy summer day Monday, with a high in San Jose of 79 degrees, far below the record temperature of 97. Oakland was even cooler at 74, and as usual, San Francisco's high of 70 was cool enough to bring out jackets. But beneath that simmering surface calm, the ground was heating up at a record rate -- and the California weather landscape was shifting with it.

Just how fast the state's climate is changing became apparent Monday when the National Oceanic and Atmospheric Administration released figures showing the first six months of this year were the hottest the state has ever recorded -- breaking the mark by a single degree after 80 years. That record came hot on the heels of 2013, California's warmest year ever. And the NOAA figures came just four days after the National Drought Mitigation Center unveiled a map that revealed 81 percent of California is experiencing "extreme drought" conditions.

Under normal circumstances, drought and heat aren't necessarily connected -- it can be bone dry even when temperatures are mild -- but for the first time in decades, experts theorized that the drought is now affecting how hot it gets.

"When you have these increased temperatures, you have more evaporation, and the plants are transpiring more," said Brian Fuchs, a climatologist for the Drought Mitigation Center at the University of Nebraska. "The temperature component compounds the dryness component."

At San Jose's Rose Garden on Monday afternoon, artist Al Preciado and a small group of fellow painters and poets were wrapping up their brushes, canvasses and notebooks. A San Jose native, Preciado said this year has felt different.


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"It's been very hot, very uncomfortable the last month or so," Preciado said. "I wonder if it's a result of global warming."

Almost from the first moment the phrase "global warming" was ever uttered, its political subtext heated up formerly benign discussions about the weather. Eventually, the less inflammatory expression "climate change" took hold.

"Once you get dry conditions, it actually becomes warmer," said Daniel Swain, author of the California Weather Blog, "because more of that heat from the sun is going into heating the air and the ground, rather than evaporating water."

The daily mean temperature for the first half of the year in California was almost five degrees warmer than the average for the 20th century, according to figures from NOAA's National Climatic Data Center. San Francisco and Sacramento were among the Northern California cities with record-breaking heat, although San Jose was spared -- somewhat -- with an average daily high temperature of 72.45 degrees, only the seventh-hottest first six months on record.

One way the big heat and the little rainfall clearly are connected is by a mountain of high pressure -- Swain nicknamed it the "ridiculously resilient ridge" -- that kept last winter's storms from dropping much moisture on Northern California. Most of those soakers took one look at the Golden State and high-tailed it straight to Canada. "What we're experiencing now isn't surprising," said meteorologist Jan Null, of Golden Gate Weather Services, "because the same high pressure that gives us warm weather gives us dry weather. They go hand in hand."

And both hands were as dry as the tinder that threatens the state with its worst wildfire season in many years. "It looks like we're going to have a really bad fire season," Swain said. "That may be how the drought is most acutely felt."

At the Rose Garden, painter Pia DiStefano recalled a recent outdoor art show, when it rained for about three minutes, catching everyone off guard. "It was like snowflakes in the middle of the desert," she said.

Contact Bruce Newman at 408-920-5004. Follow him at Twitter.com/BruceNewmanTwit.

monday's highs
Livermore 81
Oakland 74
San Francisco 70
San Jose 79