Here are some hot tips -
Dress them comfortable
When dressing babies, toddlers and children in the hot weather, make sure they wear very loose clothing. Let their skin breathe! Most parents put their babies in vests/rompers. Make sure you try and put a sun hat on every child. I try with my youngest but its a fail everytime since she keeps throwing it off ha ha.
Because babies/toddlers and children are constantly on the go and being in the sun they will sweat much more! So they are more likely to get heat rashes! So make sure you bath them properly, and wash them properly on their necks, under their arms and behind their knees!
Food and drinks
During this weather my girls haven't been eating very hot meals as usual, they've had more of Salads, Pasta, Meat, Snacks, Fruit and a lot and a lot of drinks! Make sure they have a lot to drink too keep them hydrated!
Prevent Summer Illnesses
Keep away from large crowds - Very easy to catch any infections/illnesses this way. So try and keep away.
Keep away from direct sunlight- and try and keep way out and maybe stay inside if there are hot winds. Plaster them in sun cream, use the strongest one - 50+.