▁to ▁the ▁Sah el , ▁and ▁the ▁Sah ara . ▁The ▁veget ation ▁consists ▁pre domin antly ▁of ▁grass land , ▁especially ▁sav anna ▁with ▁clusters ▁of ▁dr ought - res istant ▁trees ▁such ▁as ▁ba ob abs ▁or ▁a ca cias . ▁Between ▁December ▁and ▁April ▁is ▁the ▁dry ▁season . ▁The ▁wet ▁season ▁is ▁between ▁about ▁July ▁and ▁November ▁with ▁an ▁average ▁annual ▁ra inf all ▁of ▁ 7 5 0 ▁to ▁ 1 0 5 0   mm ▁( 3 0 ▁to ▁ 4 0   in ches ). ▁The ▁highest ▁temper atures ▁are ▁reached ▁at ▁the ▁end ▁of ▁the ▁dry ▁season , ▁the ▁lowest ▁in ▁December ▁and ▁January . ▁However , ▁the ▁hot ▁Harm attan ▁wind ▁from ▁the ▁Sah ara ▁blow s ▁frequently ▁between ▁December ▁and ▁the ▁beginning ▁of ▁February . ▁The ▁temper atures ▁can ▁vary ▁between ▁ 1 4   ° C ▁( 5 9   ° F ) ▁at ▁night ▁and ▁ 4 0   ° C ▁( 1 0 4   ° F ) ▁during ▁the ▁day . ▁ ▁Tour ism ▁& ▁Park s ▁ ▁M ole ▁National ▁Park ▁B ui ▁National ▁Park ▁( now ▁def unct ▁due ▁to ▁B ui ▁National ▁Dam ) ▁Lar ab anga ▁Historic ▁Mos que ▁We chia u ▁Hi ppo ▁San ctu ary ▁ ▁Dem ograph ics ▁The ▁Sav ann ah ▁Region ▁has ▁a ▁low ▁population ▁density , ▁and , ▁along ▁with ▁the ▁official ▁language ▁of ▁English , ▁most ▁inhabitants ▁speak ▁a ▁language ▁of ▁the ▁O ti – Vol ta ▁sub