It’s generally best to avoid cleaning windows in direct sunlight. The sun’s heat can cause the cleaning solution to dry quickly, leaving streaks and residue on the glass. Additionally, the rapid evaporation of the cleaning solution can make the cleaning process more challenging and lead to an uneven finish. Optimal window cleaning conditions include a cloudy day or choosing early morning or late afternoon when the sun is not directly shining on the windows. This allows for a more controlled application of the cleaning solution and ensures a thorough, streak-free result for sparkling, crystal-clear windows.