If you're a fan of a glass of ice-cold lemonade on a particularly warm summer afternoon, you may have noticed that lemons—which are usually a bargain fruit—are sporting pretty high price tags right now. So, why are many supermarkets selling lemons for nearly double their usual price?

The Produce Alliance, a massive industrial distributor of fresh fruit and vegetables, is pointing the finger at warmer weather. In July, the group released a "market alert" to clients that spelled out exactly why the industry's supply of lemons has dwindled.

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"Due to an extremely hot spring, the majority of the fruit crop matured much earlier and we are now experiencing shortages across all lemon varieties," the alert read.

Higher temperatures in California, where much of the United States' lemon supply is grown, caused wholesale prices of lemons to nearly double. The U.S. Department of Agriculture reported wholesale prices of lemons ranging between $53 and $64 in various markets across the U.S. in early August, which is $5 more than it was in July. In June, cartons of lemons sold for $33, The Packer reports.

Unseasonably hot weather has affected more than just lemons—Valencia oranges, also grown in the California region, are now approaching record highs as well. It's unclear if demand is higher than normal in the summertime, but sales representatives are advising clients to switch to limes until more lemons are harvested in the fall.

Thinking of buying limes instead? Check these out:

Image zoom Daniel Grill

The American fruit industry imports about 40 percent of their citrus from South American countries, says Zak Laffite, a sales rep for California-based Wonderful Citrus, but hot weather has also affected lemon crops in Mexico and Chile.

“The overall Mexican lemon crop is expected to be down by 15-20% because of a cold front in December that affected trees in the colder regions of Mexico’s lemon growing regions in the north,” Laffite told The Packer. “Chile, on the other hand, is projecting a lemon crop very similar to last season, but their shipments to the U.S. are down by 30% against the same time last season. They haven’t been able to harvest as fast as last season due to rain/weather disruptions and a later crop.”