▁is ▁at ▁the ▁convergence ▁of ▁two ▁ancient ▁roads , ▁the ▁T ō ka id ō ▁and ▁the ▁R iku zen - H ama ▁Ka id ō . ▁ ▁Geography ▁I wan uma ▁is ▁in ▁the ▁east - center ▁Mi y agi ▁Pref ect ure , ▁border ed ▁by ▁the ▁Pacific ▁Ocean ▁to ▁the ▁east . ▁It ▁is ▁also ▁located ▁at ▁the ▁mouth ▁of ▁the ▁Ab uk uma ▁River . ▁ ▁Ne igh bor ing ▁municipal ities ▁Mi y agi ▁Pref ect ure ▁N atori ▁Sh ib ata ▁Mur ata ▁Wat ari ▁ ▁Dem ograph ics ▁Per ▁Japanese ▁census ▁data , ▁the ▁population ▁of ▁I wan uma ▁has ▁increased ▁over ▁the ▁past ▁ 4 0 ▁years . ▁ ▁Cl imate ▁I wan uma ▁has ▁a ▁hum id ▁climate ▁( K ö ppen ▁climate ▁classification ▁C fa ) ▁character ized ▁by ▁m ild ▁sum mers ▁and ▁cold ▁winter s . ▁ ▁The ▁average ▁annual ▁temperature ▁in ▁I wan uma ▁is ▁ 1 2 . 6   ° C . ▁The ▁average ▁annual ▁ra inf all ▁is ▁ 1 2 5 2   mm ▁with ▁September ▁as ▁the ▁wet test ▁month . The ▁temper atures ▁are ▁highest ▁on ▁average ▁in ▁August , ▁at ▁around ▁ 2 4 . 9   ° C , ▁and ▁lowest ▁in ▁January , ▁at ▁around ▁ 1 . 6   ° C . ▁ ▁History ▁The ▁area ▁of ▁present - day ▁I wan uma ▁was ▁part ▁of ▁ancient ▁Mut su ▁Province , ▁and ▁the ▁Take k oma ▁In ari ▁S hr