Your growing season is pretty close to over if those temps are maintained. Most(but certainly not all) plants can take a light, brief frost, but the rate they grow and ripen is reduced as day length shortens. As frosts arrive day length is greatly reduced so it is a double whammy.

We were at 2C this morning my sunflowers look like they are doing great so far. Most of them are finally making seeds so I am hoping they will finish. Also, my corn is finally starting to make cobs... I'm not holding out much hope for that one!

It will tolerate cool morning weather, but not frost. It may survive 30 or 31 for a short period, but garden sunflowers are fairly frost sensitive. When frozen, the leaves will respond like your tomatoes and squash--they will wilt when they thaw, then turn black.

oh that would be great to see any of them seed but that won't happen for obvious reasons I don't believe my largest sunflower will even flower but it is soooo close to flowering it's almost a coin toss because after a few days into october anything could happen with frost ,even one or two good hard frosts is more likely than not . According to watching the rest of them flower , I would guess I am about 5 to 9 days away from my largest one flowering . I've been doing a photo journal and as of this morning it is now slightly more than 11 feet 7 inches to the flower ...it will get over 12 feet. No frost warnings in the near or even distant forecast (it could change )and in the next 5 days it will be as low as 35F with wind chill and as high as 75F . So as you can see my sunflowers are living on the edge a few of them look a little beat up but even they are producing a larger and larger flower head with each passing day . Thankyou for the heads up on the signs of weather tolerance and damage .

Is getting very cold in Alaska 32 at night. Have 2 giant sunflowers that are not blooming yet but ready to bloom. Could I bring them inside to save them?