The freeze gripping the West appeared on the verge of easing Tuesday, but farmers who spent millions to protect crops were still assessing damage, some produce prices climbed, and businesses and residents dealt with burst pipes.

The National Weather Service predicted another frosty night, but said temperatures would begin to warm as high pressure moved east.

For a fifth night, temperatures in the San Joaquin Valley, California's agricultural heart, dipped below freezing, though they were a few degrees warmer than previous nights, said Paul Story of Exeter-based California Citrus Mutual, an association of citrus growers.

Growers, who have about $1.5 billion worth of citrus fruit on the trees, used wind machines to keep warmer air closer to the ground and irrigation to raise temperatures.

Citrus growers statewide spent more than $23 million over five nights to save their crops, the association estimated.

But in some areas, that wasn't enough.

"We definitely had some damage, but it's hard to tell how much," Story said, adding that the fruit's maturity and high sugar content helped protect much of the crop.

Crop damage estimates weren't yet available, growers said, because for some varieties damage isn't visible for days or weeks. Initial reports indicated up to 6 percent of the state's orange crop was damaged and up to 9 percent of the mandarin crop, Story said.

Despite damage, Story said, plenty of good citrus is left on trees.

"The fact is, we have a lot of good quality fruit to sell," Story said.

Wind machines and irrigation would run in groves for least two more nights, he said. A freeze warning was issued for the areas around Hanford, Lemoore and Tulare in the San Joaquin Valley, starting at 7 p.m. Tuesday and ending at 10 a.m. Wednesday, according to the National Weather Service.

California's strawberry growers also were using wind machines, sprinklers and helicopters, said Carolyn O'Donnell with the state Strawberry Commission. In Oxnard and Santa Maria, growers who lacked frost protection saw damage to flowers and fruit in their early berry varieties.

In urban centers, it was 39 degrees in downtown Los Angeles early Tuesday, while San Francisco had 37 and San Diego, 36. In Oakland, black ice caused several crashes.

Some Lake Tahoe casinos on the California-Nevada border were cleaning up after below-zero temperatures caused water damage. The temperature dropped to minus 11 on Monday at South Lake Tahoe, but was expected to warm slightly by Tuesday.

Pipes burst at Harrah's casino and sent thousands of gallons into the main, 18-story tower and a high-roller gambling area, said Tahoe-Douglas Fire Marshal Eric Geuvin. Flooding temporarily disabled elevators, damaged slot machines and caused an evacuation.

Two sprinkler heads broke at Harvey's casino, and another broken pipe sent water into the loading dock at the Horizon casino. At the MontBleu, an antifreeze system meant to prevent pipe breakage froze, he said.

Sparks, Nev., declared a state of emergency Monday, mostly to free up money to repair a pair of 7-foot diameter sewer lines that broke.

Homeowners reported pipes breaking from Flagstaff, Ariz., to Las Vegas, where Monday's high of 38 degrees was the coldest on record for the date. But a rare freeze warning expired Tuesday as temperatures warmed.

In New Mexico, some public facilities opened later than usual Tuesday because of freezing temperatures and poor driving conditions. School districts from Albuquerque west to Gallup were also on two-hour delays Tuesday morning.

And in Flagstaff, which saw the final day of the coldest five-day stretch the mountain city had seen in more than 22 years, firefighters on Monday picked up two homeless people who passed out on the streets.

The cold also damaged the southwestern lettuce crop. In Yuma, Ariz., an area which provides much of the nation's leafy greens during the winter, farmers reported damage to romaine and iceberg lettuce crops.

Victor Smith of JV Smith Companies, which farms 15,000 acres of vegetables in Yuma and Mexico, said workers had to peel off layers of lettuce that turned brown before selling it.

"It's creating a lot of extra work and strain," Smith said. "Right now supplies are very tight and the market is very uncertain."

Kurt Nolte, an agricultural agent for the University of Arizona, said that translates into higher prices for the consumer. The price for a head of iceberg lettuce recently doubled to $2 at a grocery store. Cartons of lettuce during the warm spell were selling for $8 but now are as high as $30 on the spot market, he said.

"We are going to be suffering from a shortage of some vegetables for about three weeks because of the production gap," Nolte said.

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Associated Press writers Scott Sonner in Reno and Felicia Fonseca in Flagstaff contributed to this report.