Almost all hydrangeas are deciduous and typically lose their leaves in winter so now is a completely acceptable time of year for them to start entering the dormancy process with the leaves browning or changing color before dropping off altogether.

Just make sure that your potting soil is not getting soggy. When Fall arrives, you should be able to reduce the amount of water somewhat (from summer levels). And once the plant goes dormant and there are no more leaves and blooms to take of, you may be able to reduce it a little more. But perhaps set up an electronic reminder so you will not completely forget to water now and then during the rest of Fall and all of winter.

I assume because this is also posted to Balcony Gardens that your potted hydrangea is outside (actually the preferred location, as hydrangeas won't survive long as indoor plants). If so, your climate in fall and winter is very similar to mine. I grow a number of hydrangeas in containers that remain outside year round. Once the heat and dryness of summer is past, I never have a need to water them....rain does a perfectly adequate job :)

But the comment about the soil not staying too soggy is important. You want the potting soil mix to be sufficiently fast draining that exposure to the elements does not leave it overly wet.

Thanks all for the guidance. Here is a pic of the hydrangea, it is indeed outside in the balcony. I am hoping the leaf color is normal for this time of the year. This is the 1st time I have potted a hydrangea so the advice from all of you helps...thanks a lot !

It is common to get the colors of those large leaves in the Fall but I see some small leaves at the bottom of the picture that are too light green, even for small new leaves (unless the look is because the sun is shining at them too strongly so they instead appear to be light green but are not). If they are that light green, it may be low on some minerals. In that case, I would fertilize with low-or-zero nitrogen fertilizers.

My hydrangea leaves often turn that exact color as they start breaking down the summer chlorophyll and pulling nutrients down to the roots. 100% normal color at this time of year. But I envy your ability ongrow these in pots in your far more reasonably climate. Here it gets to about -30C or a bit below -20F most winters so they don’t survive in pots.