By Nicholas Christen and Craig Miller

Craig Miller / KQED

Even tomatoes can only take so much heat. A belt from Bakersfield to the northern Sacramento Valley produces a third of the nation's canning tomatoes.

Autumn is here, so says the calendar. Living on the coast, it might be easy to think that California escaped the heat wave suffered by much of the nation this summer. While that may be true for most of the large coastal population centers, it was a different story for much of the state’s interior farm belt.

Throughout June and July, even Central Valley spots escaped much of the heat felt by the Great Plains, though Cal Expo officials blamed the heat, in part, for tamping down attendance at the state fair. Then things heated up quickly — especially in the Sacramento and San Joaquin Valleys — through August and into September.  Valley towns including Redding, Red Bluff, Sacramento, Merced, Madera, Fresno, and Bakersfield, have been on the order of three-to-five degrees above normal for the duration of August and September.

Fresno saw 27 days above normal during August and most of those days were at least three degrees above normal, a string one meteorologist at the National Weather Service in Fresno called, “pretty amazing.”

Even Central Valley farmers, who are used to triple-digit days, were taken aback.

“Yeah, this summer has been one of the hottest that I remember,” said Don Cameron, who runs 7,000 acres of crops for the Terranova Ranch, southeast of Fresno. He’s been farming the Valley for 30 years.

“Our tomatoes have taken a little bit of a beating from the 110 degree weather we’ve had, but with the drip irrigation we’re able to keep them a little fresher, a little cooler when it does get hot like that.”

On the day we visited Cameron, the fever seemed to have broken. “Yeah, we’re in the low 90s today,” he snorted. “It’s like — like a spring day.”

“We had just a couple of weeks on end where we were 109, 110, 111 degrees. Just brutal. The nights don’t cool down, it’s hard on the plants, it’s hard on the people.

There has been a plus side to all this.

“I can remember we used to get a lot of real severe frosts during the spring growing season,” recalled Cameron. “I can’t remember the last time we had one that was actually a killing frost during April.” That’s created an opportunity of sorts for growers. “We’ve been able to plant our tomatoes earlier in the year for earlier harvest, which extends the, the season for the cannery.”

The roast continued well into September, bringing with it an unusual late-season streak of 90-plus-degree days in downtown Sacramento. This year could eclipse the September record of 20 days, set back in 1899.

August was more than four degrees above average in Sacramento.

See more on how climate change is challenging California farmers on the documentary, Heat and Harvest. It premieres Friday evening on KQED TV.