Are they in the greenhouse?

Mine are, I spray them overhead this weather but only when they are in the shade, I wet the floor too to give a humid 'bouyant' atmosphere, you can do similar outside, its so hot and dry I think thats your problem......

if they are outside [like mine] then yes, they do have flowers at the moment, as everything is late this year, but the flowers will soon be tiny tomatoes.They need watering every day, and when tomatoes appear start feeding them.

If the flowers are falling off, and there are no signs of any tomatoes, then it's likely that they haven't been pollinated, try giving the canes a gentle tap each time you pass them, this helps pollination, Derek.