Just had a new roof installed with all new plywood etc. Looks like a fine job except that most of the shingles do not lie 100%flat on the bottom. Someone told me that it's because the weather is still cold (it was installed beginning of December in NY) and that if it were warm, that the shingles would have flattened from the heat.

Is this true or should I call the roofer back to fix?

Much thanks for answers :)

You heard right. Until the weather warms up, the shingles will stay pretty much the way they are now. I am sorry you had a roof installed during your colder season. Here in Florida a new roof will "lay down" rather quickly and with hurricanes being more of a concern than any other weather, we roofing types count on just that.

This is correct it will take a hot day to get them to lay flat, and as noted they will most likely stay the way they are now till spring and you get several good hot days

Thank you both! I'm at ease now :)

Merry Christmas & Happy Holidays!

It may just be that the shingles need some warm sun and everything will be fine. A more serious problem could be that they shingled over extremely buckled felt paper. Most felt paper will not lay tabletop flat in cold weather. Check the roof by applying pressure to areas of the roof . You should be able to see the difference. Are corners of the shingles just sticking up or does it feel like air pockets under the shingles. If it is the felt come spring it will look better but will never be completely flat. Felt does relax with heat but with hundreds of nails through it from the shingles, it will not lay completely flat.

There all right, wait till it warms up and the tar strip on back will stick them down for good