Most states have a list online showing when various crops, including fruit, are coming into produce auctions and farmers market. They also tell when the normal peak is for that produce. During the peak, prices are extremely low because of all the competition to sell. It's a great time to buy peak flavor, very cheap produce.
Here's Ohio's list.
Typical Vegetable and Fruit Harvest Dates in Ohio
VEGETABLES Early Most Active Late
Asparagus April 23 May 1 - May 30 June 25
Broccoli June 20 July 1 - October 31 November 30
Cabbage June 1 June 10 - October 31 November 15
Cauliflower September 1 Oct. 5 - November 20 December . 5
Collards May 15 August 20 - October 31 November 20
Cucumbers June 25 July 5 - August 15 September 15
Eggplant July 10 July 20 - September 30 October 15
Lima Beans July 10 July 15 - August 31 October 31
Okra July 15 August 15 - September 15 October 15
Onions June 25 June 25 - July 31 September 30
Peas May 20 June 15 - June 25 July 5
Peppers July 5 July 15 - October 31 Nov. 5
Potatoes July 10 July 20 - September 30 October 15
Pumpkins September 15 October 1 - October 15 October 31
Snap Beans June 10 June 20 - July 20 August 31
Squash June 15 June 25 - September 1 September 30
Spinach April 15 May 5 - June 25 June 30
Sweet Corn July 1 July 5 - August 31 September 25
Tomatoes July 5 July 10 - September 15 October 15
FRUITS Early Most Active Late
Apples July 15 September 1 - October 25 October 31
Blackberries July 10 July 15 - July 30 August 10
Blueberries June 15 July 5 - August 10 August 31
Cherries June 10 June 20 - July 25 July 25
Grapes August 25 September 10 - September 20 September 30
Peaches, Nectarines July 5 July 20 - September 1 September 15
Plums July 1 August 1 - September 30 October 15
Pears August 1 August 10 - August 31 September 10
Raspberries July 1 July 15 - August 15 September 20
Strawberries May 20 June 1 - June 10 June 25
OTHER Early Most Active Late
Flowers, Herbs July 1 July 15 - September 15 October 1
This interactive map gives a pretty good idea when the different produce, including apples, is available in your state. It also shows the peak dates
http://www.pickyourown.org/index.htm#statesKeith