SACRAMENTO — As if the drought weren’t enough of a challenge for California farmers, the summer is expected to be exceptionally hot.
The U.S. Climate Prediction Center envisions above-average temperatures over the next three months throughout the West, perhaps putting more pressure on trees and crops already stressed from a lack of water.
Many parts of the Central Valley have already experienced triple-digit heat, but National Weather Service meteorologist Tom Dang doesn’t expect a long string of 100-degree afternoons — at least yet.
“It’s a little too early to say about the duration of heat spells at this point,” said Dang, who is based here. “That tends to be a much more short-term phenomenon. Certainly there are going to be some temperatures over 100 degrees, at least for a few days.”
In May, brief hot spells punctuated periods of balmy weather, including last week when a low-pressure system brought an unsettled weather pattern marked by mountain showers and isolated thunderstorms before temperatures heated up again during Memorial Day weekend.
This week, another low pressure system off the coast of the Pacific Northwest kept Northern California cooler with locally breezy conditions, according to the weather service. However, temperatures were expected to rise above normal in most areas by next week.
Prolonged or untimely heat can take its toll on crops. Last summer, several days of extreme heat in June in the Sacramento Valley caused plums grown for prunes to drop from trees just as the crop was developing. Then another heat spell around the Fourth of July spoiled part of the fresh tomato crop.
Two years ago, a prolonged August heat spell in the Central Valley caused early almond varieties to come in lighter than expected. Hot temperatures also cause Valencia oranges to re-green, which brings the export season to an end quickly because growers have to treat with an ethylene gas that’s frowned upon in some export destinations.
The heat could also worsen drought conditions that are already historic. The Climate Prediction Center expects drought conditions to persist or intensify throughout California and much of the West through August.
The agency still anticipates that El Nino conditions will develop during the summer, which portends storms coming in from the south. El Nino brought welcome relief from a three-year California drought in the winter of 2009-2010, when a persistent parade of rain clouds filled reservoirs and broke precipitation records.
But El Nino is by no means a guarantee of copious amounts of rain and snow, especially in northern areas where the rain is needed to replenish reservoirs, National Weather Service warning coordinator Michelle Mead has said.
Here are the May and seasonal rainfall totals and comparisons to normal for selected California cities. Totals are as of May 27.
Redding: Month to date 0.15 inches (normal 1.57 inches), season to date 17.77 inches (normal 33.65 inches)
Eureka: Month to date 0.58 inches (normal 1.54 inches), season to date 20.76 inches (normal 39.34 inches)
Sacramento: Month to date trace inches (normal 0.59 inches), season to date 9.79 inches (normal 18.22 inches)
Modesto: Month to date 0.01 inches (normal 0.56 inches), season to date 7 inches (normal 12.92 inches)
Salinas: Month to date trace inches (normal 0.31 inches), season to date 5.89 inches (normal 12.7 inches)
Fresno: Month to date 0.04 inches (normal 0.38 inches), season to date 4.81 inches (normal 11.24 inches)
Here are the percentages of capacity for California reservoirs and comparisons to their seasonal averages as of midnight May 26, according to the Department of Water Resources California Data Exchange Center:
Trinity Lake: 50 percent of capacity, 58 percent of average
Shasta Lake: 49 percent, 57 percent
Lake Oroville: 50 percent, 59 percent
Folsom Lake: 57 percent, 69 percent
New Melones Reservoir: 34 percent, 53 percent
Millerton Lake: 59 percent, 77 percent
Pine Flat Reservoir: 41 percent, 59 percent
San Luis Reservoir: 43 percent, 53 percent