The 2 largest cities in Idaho are Boise with a population of  145,987 and Nampa with 81,557. The next 3 largest cities are  Meridian with 75,092, Idaho Falls with 56,813 and â¦ Pocatello with  54,255.
Averages for Washington DC in September. The weather in September in Washington DC is very attractive for those that want to avoid the peak heat of summer, yet still enjoy lots of warm days on their visit. On average, peak temperatures during the day in September still reach up to 27Â°C.
Best Times to Visit Washington D.C. The best times to visit Washington, D.C., are from September to November and March to May. In the autumn, the sweltering summer is gone, taking with it most of the high-season tourists. All that's left are crisp breezes and changing leaves, which, by the way, look great against all those marble monuments.