Central Europe 15 Day Tour

Weather varies so much theses days.
The weather charts on the the tour page are probably as useful as anything.
https://www.ricksteves.com/tours/eastern-europe/central-europe-tour

I'd say it can be quite hot in Central Europe at that time of year, but it depends on the year, the exact location, and your frame of reference. Here are actual, day-by-day weather statistics for Budapest last August, from the website timeanddate.com:

Budapest weather -- August 2024

You can--and should--use the pull-down box to the right, just above the graph to take a look at early September and both months in other recent years. The Search box will give you access to info on other cities you plan to visit.

And what you will discover is that the weather isnt the same on the same date every year. Some times cooler and some times warmer. Darn inconvenient. And, agian, Central Europe is a big place so if you compare Prague to Budapest ...... and do try and find a site that is in F and not C. Who understands that C stuff?

I live in "Central Europe" and life goes on as normal all summer long. Actually cooler here than where I came from in Texas. Most of us, and most businesses, do have AC these days. Also keep in mind that the horrible sounding high temperature isnt the temperature all day.

I think the detail examination of the weather is unproductive. It will be what it will be when you get there. But if you want to dive into it, this is I think the best site: https://weatherspark.com/s/84771/1/Average-Summer-Weather-in-Budapest-Hungary

But in a broad generalty, the later in September the cooler things will be. As for rain, it varies by location but its a fairly dry climate and not the wet season where the RS tour goes.

We did this tour two years ago in September and it was hot. Maybe we wore light jackets late at night/early in the morning, but not often.

Larry specifically said he is "trying to figure out the best time to go". I think it makes sense to look at recent historical weather patterns when one has that flexibility. Why would you want to go somewhere and potentially expose yourself to day after day of 90+F temperatures if you had other options?

I admit that it's tricky, because if one goes too late in the year, one could bump into autumn, and some of us are not fond of chilly + rainy, either.

I dont disagree. I just dont think mabye we try and be more accurate than out tools will permit.

The weatherspark site does give you

The daily average high (red line) and low (blue line) temperature,
with 25th to 75th and 10th to 90th percentile bands. The thin dotted
lines are the corresponding average perceived temperatures.

Which shows the High temperature on September first in Budapest is somewhere between 65F and 85F (precentile bands above and below average). Thats the best you are ever going to guess. Oh, I maybe you could say because of global warming that the odds are better between 76F and 85F than below 76F .... but if you look at 2024 there September was below the average and so was July i think (the weatherspark sites shows you that data too in a nice graphic format).

Good news is on that 15 day tour he will be on an ariconditioned bus the better part of 6 days.