If you can get hold of some UK ATPL notes for meteorology you should find 'climatology' information there that will cover the areas you fly in. Or, do you know any ex RAF pilots who kept their manuals when they left the services? There was a book published by HM Stationery Office in the UK called "The Handbook of Aviation Meteorology", this book was a 'must' in the old days, possibly this or something similar still is and fellow pilots that went the UK route may still have a copy, you could try this also.
Finally,
this page of Google search may help, they mention a book produced by Oxford at around GBP54:00!
Hope this helps.