Eating what is in season makes it easier for us to shop locally. Not only is the food fresher (and often more nutritious) but we reduce the amount of energy used to transport it which is better for the environment. Learn more about eating seasonally over at Sustainable Table.

Finding out what is in season in your area is the first step. Thankfully, it’s a pretty easy one whether you are shopping at a chain grocery store or a local Farmer’s Market.

Peak Season is an interactive map of the US where you can find a state at any time and it will tell you what produce is currently in season. It’ll also give you a description for each plant along with recipe ideas.
Eat the Seasons is available for the US, Canada, UK and Ireland. It is updated weekly.
Another option if you are in the US or Canada is this Eat Well Guide. Click on your state/province and you will find a chart of various fruits and vegetables and when they are in season.
Here is a sample of what is currently in season for British Columbia, Canada:

Apples, Artichokes, Basil, Beans (fresh), Beets, Blackberries, Broccoli, Brussel Sprouts, Cabbage, Carrots, Cauliflower, Celery, Chives, Cilantro, Corn, Cucumbers, Fennel (bulb), Garlic (fresh), Grapes, Green Onions, Hazelnuts, Kale, Lettuce, Leeks, Melons, Onions (sweet), Onions (cooking), Parsleys, Parsnips, Pears, Peppers, Plums, Potatoes, Pumpkins, Quince, Radishes, Rosemary, Rutabagas, Sage, Salad Greens, Spinach, Swiss Chard, Tomatoes, Thyme, Turnips, Winter Squash.

And in California, USA:

Apples, Asparagus, Avocados, Basil, Beans, Green Beets, Brussels Sprout, Cabbage, Carrots, Celery, Chili Pepper, Grapefruits, Lemons, Oranges, Collards, Corn, Cucumber, Eggplant, Grapes, Guava, Pineapple, Kale, Kohlrabi, Lettuce, Mushroom, Mustard, Nectarines Okra, Peaches, Pears, Peppers, Persimmons, Plums, Potatoes, Raspberries Spinach, Strawberries, Tomatillos, Tomatoes.

Also, check out Local Harvest to find Farmer’s Markets and other places near you where you can purchase in season goodies! Locavore is an iPhone app that does the same thing plus you can find recipes and share with friends, all for free.