The price of tomatoes — tart bursts of flavor in salads and sandwiches — surged nearly 40% in April from a year ago on a combination of bad weather, high tariffs and climbing transportation costs.

Overall, food prices in grocery stores rose 2.9% in April from a year ago and were up 0.7% from March, according to the consumer price index.

Fresh fruits and vegetables — perishable items that faced higher shipping and trucking costs as fuel prices surged in the past month — soared 6.5% in April from a year ago.

While prices for bananas and citrus fruits also climbed, the real culprit for much of the steep rise was tomatoes.

By some estimates, more than 70% of the fresh tomatoes consumed in the United States come from Mexico, where unseasonably wet weather and disease resulted in below-normal yields. And freezes in key growing areas of Florida early in the year also affected the tomato crop.

Tariffs on Mexico have also pumped up prices.…