Short answer
Adjust or swap the sprinkler heads that reach your house so they spray away from the walls, shorten their arc, and water early in the morning. Then keep the glass on a regular cleaning schedule so any spots that do land never have time to bake on.
Find the culprits
Run each zone for a minute and watch. Usually it's one or two heads — often in a narrow side yard or right behind the house — doing all the damage. Note which windows they hit.
Fixes that work
Rotate the head or shorten its arc so it stops short of the wall
Lower the pressure or swap in a shorter-throw nozzle for beds near the house
Replace spray heads next to the house with drip irrigation for flower beds
Water in the early morning so drops dry slower and the sun has less time to bake minerals on
Check again after mowing or aerating — heads get knocked out of alignment
Then reset the glass
Once the spray is under control, a professional cleaning resets the windows. If the spots have been there a season or more, they may need a hard-water treatment. On homes with a lot of irrigation, a Quarterly plan through summer keeps it from building back up.
Rather have a pro handle it?
Pro Solutions does window cleaning across Boise and the Treasure Valley. Quotes are free, itemized, and usually texted the same day.