Drought does not explain everything

Some varieties of fruit are very early and some vegetables are very rare in California.

According to the producers it is not drought or low rainfall for 4 years which is the major factor in these problems but rather the 2 "hot" successive weather.

These higher than normal temperatures during the winter pushed plants to grow faster and the fruits to ripen early, disrupting schedules of planting and production.

Some vegetable seasons are shortened to three weeks , having started much earlier than the scheduled date. Lettuce, celery , broccoli and cabbage this year were 2 to 3 weeks in advance.

The relatively cool temperatures in April , on the contrary , slowed growth . Lettuce has seen its price double from last year , other varieties of salads increased 50 %. 

source : los angeles times com