The sun is out, the sky is blue, there's not a cloud to spoil the view but you've got droopy leaves!
So you give your affected plants a good watering, move them into the shade if they're in a large pot and give their leaves a misting with the sprayer. Hopefully, their leaves will lose their droop and look normal again.
However, there are times when this becomes a recurring situation and more than just under-watering is the cause.
Nematodes are microscopic worms that live in the soil and affect the roots of tomato plants to the point where proper absorption is reduced and plants are unable to take up enough moisture and nutrients when the weather is hot.
This results in drooping leaves and requires foliar application of both water and feed. Unfortunately, plants affected by nematodes will not perform to their full potential.
Using fresh, sterilised soil such as that from grow bags etc. is the best way to avoid any soil based problems.