Welcome to HCM.
Understanding your concern.
As per your query you have symptoms of hyper-pigmentation of skin due to extreme hot client is because of sensitivity of your skin to Ultraviolet rays of sun. Melanocytes of skin start producing more pigment production and leads to brownish pigmentation of skin.
I would suggest you to avoid exposure to sun whenever possible and if you have to go out cover your skin with wet cloth and apply medicated sun screen TAN CARE on skin rich in spf 30. Use metarub on daily basis to wash face as it will prevent pigmentation.
Apply tea tree oil on skin dipped in cotton on daily basis to lighten pigments. Honey is also an effective agent for the same.
Use creams rich in kojic acid
at night time and rich in azealic acid at day time. At home mashed potatoes can be applied for 10-15 mins. as they will absorb dark pigments of skin.
Drink plenty of water and fluids to nourish body and keep rehydrated yourself.
Orange pulpy peel is effective antioxidant to prevent dark areas.
If you need chemical treatment go for chemical abrasion and peeling. Laser therapy
is another effective way of regaining natural skin color.
Hope your concern has been resolved.
Dr. Harry Maheshwari