Most save the date cards will not require more than a typical forever stamp (first class) when you are mailing with the US postal service, because they are usually fairly small (5x3.5 inches, 5.5x4.25 inches) and will weigh under an ounce.
Day by Day weather log for Barcelona Weather in September. September 30. Daily Comment: Temperature 25Â° C around 77 F Warm and sunny light cloud at times but generally clear skies. Day 29. Daily Comment: Temperature 25Â° C around 77 F warm and sunny. A little light cloud at times from 15:00 onwards.
During the summer, only tourists brave the large cities, as the temperatures regularly top 100 degrees. Weather during the summer is generally warm and almost every day is perfect. Northern Spain experiences cooler---although still pleasant---temperatures than the central and southern areas of the country.