Webthe extended forecast from the national weather service's des moines office for ottumwa shows a high of 52 degrees on thursday, with temperatures. Webottumwa, ia weather forecast | accuweather. Webhourly weather forecast in ottumwa, ia. Check current conditions in ottumwa, ia with radar, hourly, and more. Websunny throughout the day. A few clouds in the evening, then clear. Ottumwa, ia temperature trend for the next 14 days. Find daytime highs and nighttime lows from. Webweather tomorrow for ottumwa, ia | accuweather. Max uv index 7 high. Webfor the ottumwa area, rain is expected to kick off the system monday afternoon and then transitioning to snow in the evening and lasting through tuesday.