Are sprinklers facing your windows?
In the spring when the sprinklers get turned back on, be sure to check where each sprinkler head is spraying to insure that your windows aren’t getting hit. Windows that get hit constantly by sprinklers and then have those minerals get baked on by the high altitude sunshine will quickly deteriate and develop a layer of water stain. Water stain that stays on for months on end will be difficult, if not impossible to remove. 0000 steel wool, lime away, vinegar, and razor blades are some of the tools and products I use to removed water stain build up. There are other toxic chemicals that are much stronger and can have more significant results on water stain, but I avoid the use of chemicals for environmental and health reasons.