Hot weather - packing

Check a weather website that will predict the 10 day forecast. We went to Budapest and Prague for 10 days each last September. It rained almost every day in Budapest. It was about 55 degrees. Weather was less rainy but not much warmer in Prague. One day it did reach the predicted high of 70 degrees in Budapest. The temperature increased slowly all day until it reach 70 and then a fast decline.

I would agree with Sandy but you just never know. Hopefully will be warm and dry.in September it might get a bit cooler in the evening but shorts a t-shirts during the day should be fine.Looking at the weather forcasts for later in the month looks like mid 20'sC, but you never know.
To look like a true local wear leather sandals with socks., my mate does , even his wife tells him not to.

Today's forecast is for a high of 94 in Dubrovnik and 80 in Bansko. Or 94 in Prague and 80 in Sněžka, Czech Republic. You realize you just described a region about half the size of the United States with elevations from sea level to over 12,000 feet.

if you want to make a science out of it then go to this site: https://weatherspark.com/averages/32212/Budapest-Pest-Hungary
otherwise: http://www.holiday-weather.com/budapest/averages/

Thanks to all who replied. There is no predicting the weather. We will travel light, be flexible and use lots of deodorant.😅

Peter, serious answer. I am in the region in September and October almost every year. Budapest, Vienna, Prague, Bucharest, Sofia, the evenings are typically cool and I carry a sports coat and light sweater. that choice is because I enjoy the arts. A light windbreaker and a light sweater would work too. With one exception that I carry for the theater, my trousers are generally light weight fishing pants. Then I carry a pair of very light weight longjohns to wear under them. September and October ii still travel with just carry on. November - March I check a bag for the heavier clothing.