Can windows be cleaned in the rain?

This is a question the published glass documents do not answer, and it is worth saying so before reaching for anything else.

NGA's cleaning paper sets out a method the cleaner controls: solution applied, then removed with a squeegee. PGT, CGI and WinDoor's care guide describes its glass steps from the maker's side, a clean-water rinse first and a thorough rinse at the end "to prevent the cleaning solution from leaving a film on your glass," and it asks for each window or door to be cleaned and rinsed individually. Neither document says anything about rain falling while those steps happen. What is sourced is the rinse and the residue rule, not a rain policy.

Rain on a pane that has already been cleaned and dried belongs to another page: whether rain makes clean windows dirty.

The rule that does apply was not written for rain, but its words cover it.

Among NGA's own DO NOT items: "DO NOT allow water or cleaning residue to remain on the glass or adjacent materials." The rule names water without saying where it came from. The U.S. Geological Survey says that whether water comes out of a faucet or "falls from the sky, the water will contain significant amounts of dissolved substances, minerals, and chemicals." Rain drying on a pane leaves what it carried, the same way any evaporating water does, which is the spotting mechanism NGA's limit for pure water exists to prevent.

The residue rule does not exempt rain, and no source cited here treats rain as a rinse.

The other limit has nothing to do with the pane.

The National Weather Service's lightning safety tips are unqualified: "NO PLACE outside is safe when thunderstorms are in the area," and "If you hear thunder, lightning is close enough to strike you." The instruction is to move immediately to safe shelter and "Stay in safe shelter at least 30 minutes after you hear the last sound of thunder." NWS adds that most lightning occurs in the summer, though people can be struck at any time of year.

Thunderstorms are frequent in the Southwest Florida rainy season, which NWS's Tampa Bay office dates May 15 to October 15 while calling its start usually a transition period rather than a single date. Wind during a cleaning is a separate question, taken up on whether windows can be cleaned when it is windy, and the published prep that holds in any month is on the seasons page's working days.