Normally weather temperatures in Prague during the time of August is 16. Highs are expected to be 23 with lows around 12 celsius. We have put some more information here:
Prague, Czech Republic Weather in August FAQs
What weather can I expect?
You can expect that it will be 16 celsius but it does vary throughout the day
What is the weather like in summer?
The summer weather is 24 degrees celsius
Whats the difference in temperature between summer and winter?
Whilst it depends when you go, you can lilely expect a 16 degree difference
How cold will it get ?