I expect mine are too! As long as they still flowering and fruiting at the top, don't worry. Water and feed, if you feel you should.
As you can tell, I just let mine get on with it.
That's probably what's going to happen, the tops are still producing and flowering so what's to worry about. Sounds like a good philosophy all round.
Just looked at mine - they're yellowing at the bottom too. Am I worried?..............Nope.
Peas don't really like hot, dry weather. If it cools down a bit they might perk up again. I think our Oregon Sugar Pod are approaching their end, which isn't worrying because they've produced about 4 kilograms!
I have itchy fingers so I've been seed sorting again - this time its Mangetout peas.
Going to experiment with a January sowing of a dwarf Sugarsnap pea (Jessy, Delikata or Norli), started indoors, then planted in the GH in a pot that can be moved outside in spring.
The Bijou sown a couple of months ago in the GH are still alive and flowering which makes me hopeful for a new sowing.