In season by calendar: Here's a guide to help you identify the best produce deals month-by-month:

January
oranges, grapefruit, tangerines, tangelos, lemons, papayas, cabbages: red, white and green; leeks, broccoli, cauliflower

February
oranges, tangelos, grapefruit, lemons, papayas, broccoli, cauliflower

March
pineapples, mangoes, broccoli, lettuce

April
pineapples, mangoes, zucchini, rhubarb, artichokes, asparagus, spring peas, broccoli, lettuce

May
cherries, pineapples, apricots, okra, zucchini, rhubarb, artichokes, asparagus, spring peas, broccoli, lettuce

June
watermelon, strawberries, cantaloupe, cherries, blueberries, peaches, apricots, corn, lettuce

July
watermelon, strawberries, cantaloupe, blueberries, peaches, apricots, kiwi, raspberries, plums, cucumbers, tomatoes, summer squash, corn, green beans, lettuce

August
watermelon, strawberries, cantaloupe, blueberries, peaches, apricots, kiwi, raspberries, plums, cucumbers, corn, eggplant, tomatoes, summer squash, green beans, lettuce

September
grapes, pomegranates, persimmons, eggplants, pumpkins, tomatoes, spinach, lettuce

October
cranberries, apples, pomegranates, grapes, sweet potatoes, pumpkins, winter squash, broccoli, spinach, lettuce

November
cranberries, oranges, tangerines, pears, pomegranates, persimmons, pumpkins, winter squash, sweet potatoes, broccoli, mushrooms, spinach

December
pears, oranges, tangelos, grape fruit, tangerines, papayas, pomegranates, sweet potatoes, mushrooms, broccoli, cauliflower

Usually always priced right:
bananas, potatoes, celery