I have the chance of going on a tour to Prague and Budapest and later to Slovenia in late September-early October and am wondering what the weather is like versus wait until next year around mid May to take same trip. Realize that this is very subjective year to year but would like some feedback.
I love to travel in late September. We did that area from mid-September into mid-October. It was hot in Dubrovnik when we started out in mid-September. By the time we got to Prague in mid-October it was coldish - mid 50s for the highs - but mostly clear and sunny.
If you go in fall start north and go south, if you go in May start in south and go north.
It's Europe. Weather is totally unpredictable. Last year, I was watching the temps in Budapest from about October 1 and it was mostly cold and rainy and/or cloudy, with highs barely in double digits (Celsius). This week's forecast looks beautiful, mostly sunny and highs in the low 20's. My visit to Budapest was about this time of year and it was overcast 4 of 5 days, with light to heavy rain on 2 of them, 3 days later, when I got to Prague it was warm and sunny for 4 days (in Budapest too).
Statistically September is better weather. In practice, of 3 or more trips a year over the last 15 years i have found that the be generally true as well.
You'll have longer daylight hours in May than October.
Even though you have more daylight in the Spring; I love these old cities lit up at night!
Just my opinion.
Jean