Peas are cool season plants and don't do well in heat. In fact they die. Sounds like your plants are doing exactly what I'd expect them to this time of year.

Rodney

You don't have your zone in your post. I agree with Rodney - it's green bean season. Peas grow in cooler weather.

Pea plants do start to die in the heat, and eventually die in Summer in most places. But if the tops are still green and you have flowers, you can still get peas even if the lower plant looks bad.