Its not that high temperatures, i think we are in the same climate since temps here are in the same range as yours, but what really hurts the plants in temperature fluctuation, so having 40° today and tomorrow being 15°, those changes can really hurt the plant, but i see you have a couple seedlings coming thru already, and if they made it so far, they will make it to the end, just belive and it will grow.
Hope it helped, if it did please help by chosing my answer, its for a contest.