If the headaches are caused by the heat, then something cold is what is needed, like some icecream, or a couple of cold fruit juice drinks. Other wise like the others have suggested, keeping the children hydrated with lots of drink breaks.
If its allergies that are causing it, as with DH, keep the windows closed esp in the early mornings, and perhaps use a fan if its hot. We find its usually worse early morning...
Hope it helps..
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