Rain does not make windows dirty.
Rain is water in its purest form, like the water generated from Team Window Clean’s 3-stage water filtration system, rain water has no dissolved solids and dries spot free.
Confusion arises as rain re-distributes dirt that is already sitting on the glass from a relatively even distribution to a more concentrated distribution, often in circular shapes. The rain merely makes the existence of dirt more obvious.
All else being equal, rain on clean windows will make no difference.
Having said that, if rain is accompanied by high winds, particularly in a coastal environment, then it makes sense to wait until these conditions pass before having your windows cleaned. Strong winds can carry copious amounts of dust, salt, pollens, pollution and other debris which will become obvious once the glass dries.
Another factor in the rain debate is building run off. If rain is heavy enough and windows are not recessed or protected then rain water can potentially run down external walls, picking up dirt particles along the way and eventually settle on one or more windows.
In any case windows cleaned with pure water will attract less contaminants than windows cleaned with a squeegee as a pure water cleaning system leaves no soapy, sticky residue.
In conclusion, a moderate rain event need not influence the timing of the window cleaning process. Of course Team Window Clean will assess the timing of a job on a case-by-case basis but always in the interest of our valuable customers.