Wiper blades are one of the most neglected components on the majority of vehicles today. They are a key part to ensuring that you can see safely during rain, snow, and sleet.
Since wiper blades are not used every day and are exposed to various weather conditions, there is not a precise mileage or time interval in which to replace them. Ask yourself "How were my wiper blades working when it last rained". If you were not happy with your answer, you should have them inspected and possibly replaced.