Jason, it might be worth a try. You're going to find your temperatures approx 10 - 15 degrees higher than is best for germination, but that doesn't mean you will have no seeds germinate.

I'm assuming you are talking about common annual poppies like somniferum...The plants from last years self sown seeds are showing ripening seed pods here (and we're cooler). The majority of self sown seedlings will start to appear in Oct from ripe summer seeds, but that may be due to Aug and Sept often being dry and not entirely temperature. If you are willing to keep the area moist, you may have plants that will flower before frost.

I don't ever sow annual poppies in containers, I just don't find they transplant well enough to bother with...although I know some who do, tranplanting them when very tiny.

If you didnt mean annuals, post back :)