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.
Days of Hot Weather in Washington DC. On the hottest days in Washington DC, the thermometer reaches into the 90s Fahrenheit. Hot weather generally shows up periodically from May to September. Some years even get a 90-plus degrees day in April or October. Temperatures sometimes climb to 100 degrees or more, but that's not a yearly event.