▁to ▁early ▁sett lers ▁of ▁Del ▁Rio , ▁and ▁the ▁spr ings ▁are ▁still ▁the ▁town ' s ▁water ▁supply . ▁ ▁The ▁Del ▁Rio ▁region , ▁west ▁to ▁about ▁the ▁P ec os ▁River , ▁has ▁a ▁mix ▁of ▁desert ▁shr ub ▁and ▁ste ppe ▁veget ation , ▁depending ▁on ▁soil ▁type , ▁with ▁the ▁gray - leaf ed ▁c en izo ▁( Le uc oph yll um ▁s pp .), ▁several ▁different ▁a ca cias , ▁c act uses , ▁and ▁gr ama ▁grass es ▁dominant ▁members ▁of ▁local ▁fl ora . ▁The ▁terrain ▁is ▁mostly ▁level , ▁but ▁some ▁areas ▁are ▁disse cted ▁with ▁substantial ▁can y ons ▁and ▁d rain ages , ▁though ▁none ▁of ▁the ▁u pl and ▁areas ▁is ▁high ▁or ▁large ▁enough ▁to ▁be ▁considered ▁a ▁mountain . ▁ ▁Cl imate ▁The ▁climate ▁is ▁sem iar id ▁in ▁mo ist ure ▁and ▁subt rop ical ▁in ▁temperature . ▁Hum id ity ▁is ▁more ▁often ▁high ▁than ▁low , ▁with ▁periodic ▁morning ▁fog ▁due ▁to ▁G ulf ▁air ▁masses ▁moving ▁north west ▁into ▁the ▁area . ▁This ▁gives ▁Del ▁Rio ▁and ▁adjacent ▁areas ▁the ▁effect ▁of ▁being ▁in ▁a ▁coast al ▁dry land ▁area , ▁though ▁the ▁G ulf ▁of ▁Mexico ▁is ▁over ▁ ▁away . ▁Such ▁hum id ▁periods ▁alternate ▁with ▁periods ▁of ▁hot ▁and ▁dry ▁desert ▁air ▁masses ▁in ▁the ▁spring ▁and ▁fall , ▁or ▁cold ▁and ▁dry ▁Great ▁Pla ins ▁air ▁masses ▁during ▁winter . ▁Mo ist ure ▁rarely ▁last s ▁long ▁enough ▁for