Lot of hair fall and dandruff in dry weather, like in arizona. This hair fall and dandruff stops when I travel to california or any other city

Scalp condition. Scalp conditions like psoriasis, eczema, seborrheic dermatitis can be influenced by weather and climate, environment, stress, hormones, allergies, etc. Arizona climate probably too dry for you. There is no solution except to move! there are products which can help your scalp such as topical steroids, dandruff shampoos containing zinc pyrithione, selenium sulfide, salicylic acid, ketoconazole.