FPUS43 KDMX 190835 City Forecast for Marshalltown, IA Issued Wednesday morning - Oct 19, 2005 .Wednesday... Partly cloudy, high 57, 10% chance of precipitation. .Wednesday night... Low 38, 10% chance of precipitation. .Thursday... Mostly cloudy, high 58, 20% chance of precipitation. .Thursday night... Low 40. .Friday... High 55.