There are two things you shouldn’t do when installing a new roof: install it when the weather is too cold or when it is too hot. That’s called the Goldilocks dilemma. You want to have your new roof installed when the weather is “just right”.
In the Portland Metro area, we are blessed with a fairly mild climate. But even in our beautiful Willamette Valley there are times in Winter and times in Summer when you should consider not having your roofing installed. So what do the manufactures say? They say “shingles should be installed when the temperatures are between 40°F and 85°F. Too hot and you may tear the shingles or damage the granular coating. Too cold and the shingles become brittle which mean they may crack when bent or hammered”.
There is nothing wrong with tearing-off the old roof and preparing the roof deck as long as the weather conditions are not dangerous for the workers. It is very important that the installers of your new roofing material are able to perform their work in an environment that allows for quality, safety and reasonably comfortable conditions. In hot weather, hoses can be used to mist the shingles and keep them cool and prevent damage. In very cold weather, it is better to start on an area where the UV rays can warm the shingles and roof deck.
Most shingle manufactures do not provide a specific temperature range when their composition shingles can be installed. However, if the shingles blow off because the self-sealing wind strip did not activate, or shingles are damaged by poor hot weather installation techniques, then your on your own. The answer: Hire an experienced roofing company. A professional roofing applicator will know the tricks of the trade that will allow for the proper installation of asphalt shingles during most times of the year. Some jobs may start early, or late, depending on the weather conditions. Some jobs may only have shingles applied in the mornings or later in the afternoon. An experienced roofing contractor will also tell you if the conditions warrant waiting.