I follow the -4 degree for every thousand feet rule and it's been close. Based on that, you should expect the temps in your predictions for Langley if not even lower due to wind chill factor.

EDIT:
You might find useful-
http://mtsanjacinto.info/viewtopic.php?f=11&t=4938

Last edited by 2600fromatari; 10/02/14 12:21 PM.