The short answer
Waiting can reduce the likelihood of a clean, acceptable repair. ROLAGS recommends replacement when visible contamination cannot be removed, and its repair process requires moisture, dirt, loose glass and foreign material to be cleared before resin is introduced. NHTSA also identifies the possibility of a small crack becoming larger during normal use as a windshield-safety consideration.
Phoenix adds a practical concern: prolonged high temperatures are routine. National Weather Service climate data show that Phoenix's average first 100-degree day is May 2 and its average last is October 5. A sun-heated windshield may then experience rapid cooling when the vehicle's air conditioning starts. Heat alone does not prove a chip will spread, but temperature change, road vibration and body flex can add stress around existing damage. Until inspection, avoid pressing on the break, picking out glass, applying household resin or directing a concentrated blast of cold air at it. Keep the area dry and arrange an evaluation promptly.
