Agra, India & Beijing, China?

I would say October or maybe November.
October weather in Beijing is usually quite pleasant. Temperatures will be moderate to crisp and the smog, haze and dust storms of summer will have abated, meaning that you'll actually be able to see something on a trip out to the Great Wall. Anything later than November would be risky, plus it gets quite cold in Beijing by December.
Delhi/Agra likewise are best avoided during the summer monsoon. October and November will be warm but pleasant - especially the later into October you go, and the rain and subsequent humidity will back down to normal (or at least bearable) levels.

We visited Beijing and China in September and it was nice. The main concern about going to China is the incredible air pollution everywhere you go. Glad that I don't live there, but it is a great place to visit.
We visited four Indian ports in the SW in early April and it was HOT, 95 degrees.

I was in Agra in February and it was very comfortable and not too hot. Never been to Beijing but I am sure it is pretty cold at that time!

I was also in Agra (and New Delhi) in late February and the weather was very comfortable with no rain in the day, though perhaps there was some overnight. I was in short sleeves at the Taj Mahal but it wasn't overly hot.

Thanks all..... love this forum!

Jean

Agra (New Delhi) is good anytime but summer and winters. Both these seasons have extreme heat and cold.

Surely these aren’t in one trip? The best time for Agra is January and February - cool and dry. The temperature rockets from March onwards. Beijing is cold at this time of year - 4 degrees in February but dry. September/October is the best time for Beijing, but Agra is still around 30 degrees.

If they have to be combined in a single trip, September/October is probably preferable.