Probably too late for the giant ones. Shorter, smaller-bloomed ones might still be possible, though. Good for the birds through the winter, if nothing else!
Next year, hold some seeds back, and plant a few every few weeks, to hedge your bets against late frosts.

It is a no go with the period of light getting shorter with each passing day. As Tug has advised and as I do plant your seeds in a weekly succession. Doing this will guarantee that your garden will have sunflowers for quite a long time.

In a couple of weeks, we will be planting our second crop of sunflowers, but our growing season lasts into early December, here. The giant Sunflowers need a good 16-18 weeks to mature seeds, and I would be very surprised if your area could get that much time before serious frost appeared.

Thanks for help ,decided to purchase some potted small ones from garden centre