Hi, welcome to the forum, heat and dizziness
is quite suggestive of mild to moderate dehydration. The factors responsible for worsening symptoms when exposed to heat are-
- Evaporation of water from the skin in hot climates.
- Decreased intake of water.
- Associated conditions like diabetes, anxiety, diuretic use etc.
Dehydration can lead to irritability, confusion, rapid pulse, low BP, increased respiratory rate, dry mouth, dry skin, dark concentrated urine etc.