The average monthly rent in Des Moines reached $906 in August, up $12 from a year ago, a survey by RENTCafe.com shows. Des Moines was the only Iowa city surveyed in which the average monthly rental rates increased from July. Altoona, Ankeny, Johnston, Urbandale and West Des Moines, where average monthly rents range from $851 to $1,114, all saw slight decreases in rates compared with July. To read the survey, click here.