Use the forecast and the wall conditions
Ask the contractor which conditions the selected coating requires. Air temperature alone is not the whole decision: the surface and material conditions also matter.
Sherwin-Williams application FAQs explain that extreme conditions can affect application and finish. The product data and actual site assessment should control the work window. This guide does not give one temperature range for every paint.
Heat, sun and shade affect the work plan
The NWS Phoenix climate resources provide regional temperature and rainfall context. A forecast is useful for planning, but a sunlit wall and a shaded wall can need different attention at the same property.
Ask whether the work will follow shade, use a different sequence or pause when conditions do not suit the product. Do not read an early start as a guarantee that the whole day will remain suitable.
Rain and damp surfaces need a new check
A surface must be ready after rain or washing before coating begins. Manufacturer preparation guidance makes drying and sound surface condition part of that decision.
Avoid a fixed waiting-time assumption that ignores the material and actual conditions. The contractor should check readiness and the forecast for the selected system, including the period after application.
Agree how weather delays are handled
Agree how schedule changes will be communicated, how protected areas are left during a pause and which work can continue elsewhere. A clear weather contingency is more useful than an unconditional finish date.
If an event or travel plan affects access, explain it when requesting the estimate. The contractor can discuss a realistic sequence and its dependencies.
Request exterior painting with your location and desired timing; it is fine to enquire before choosing a start date.