A few possible causes and solution:

1. A/C is set too cold or the vents are set to window de-fog mode - Adjust the A/C thermostat for comfort cooling and/or redirect the vents to the passengers.
2. Worn-out wiper blades - Even if they look perfectly good, microscopic cracks or deformities on the edge of the wiper blades will cause smearing. Replace them regularly. 1.5-3 years is the typical wiper lifespan, depending on how often it is exposed to the sun. Use genuine and reputable brands like Bosch.