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.
So even during September you are still guaranteed warm sunshine on most days of the week. There is an average of nine hours of sunshine per day that can be expected during September in Barcelona â that's two hours less compared to August, which sees on average 11 hours of sunshine per day. During the month of September, the length of day is decreasing.