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.
However, most likely Madrid will be hot but bearable this month. The average maximum temperature in Madrid in September is 82Â°F/28Â°C and the average minimum temperature is 55Â°F/13Â°C. But average temperatures only tell half the story. Click on the link above for more on Madrid weather in September.