▁ 1 9 8 3 . ▁The ▁park ▁is ▁open ▁only ▁during ▁summer ▁from ▁June ▁to ▁October ▁and ▁it ▁is ▁covered ▁by ▁heavy ▁snow ▁for ▁the ▁rest ▁of ▁the ▁year . ▁ ▁Cl imate ▁Being ▁an ▁inner ▁H imal ay an ▁valley , ▁the ▁N anda ▁De vi ▁Bas in ▁has ▁a ▁distinct ive ▁micro - cl imate . ▁Cond itions ▁are ▁generally ▁dry ▁with ▁low ▁annual ▁precip itation , ▁but ▁there ▁is ▁heavy ▁mon so on ▁ra inf all ▁from ▁late ▁June ▁to ▁early ▁September . ▁Pre v ail ing ▁mist ▁and ▁low ▁cloud ▁during ▁the ▁mon so on ▁keeps ▁the ▁soil ▁mo ist , ▁hence ▁the ▁veget ation ▁is ▁l ush er ▁than ▁is ▁usual ▁in ▁the ▁d rier ▁inner ▁H imal ay an ▁valle ys . ▁From ▁mid ▁April ▁to ▁June ▁temper atures ▁are ▁moder ate ▁to ▁cool ▁( 1 9   ° C ▁maximum ). ▁The ▁Valley ▁of ▁Flow ers ▁also ▁has ▁the ▁micro - cl imate ▁of ▁an ▁en closed ▁inner ▁H imal ay an ▁valley , ▁and ▁is ▁shield ed ▁from ▁the ▁full ▁impact ▁of ▁the ▁south west ▁summer ▁mon so on ▁by ▁the ▁Gre ater ▁H imal aya ▁range ▁to ▁its ▁south . ▁There ▁is ▁often ▁dense ▁fog ▁and ▁rain ▁especially ▁during ▁the ▁late ▁summer ▁mon so on . ▁Both ▁Bas in ▁and ▁Valley ▁are ▁usually ▁snow - bound ▁for ▁six ▁to ▁seven ▁months ▁between ▁late ▁October ▁and ▁late ▁March , ▁the ▁snow ▁accum ulating ▁deeper ▁and ▁at ▁lower ▁alt itudes ▁on ▁the ▁shadow ed ▁southern