Last year I was in Madrid in Barcelona in mid Oct. ....the weather was lovely...warm and sunny,
...not too hot.
The south may be a bit warmer ....one can still swim in Malaga .

and Barcelona.....

To be honest, I think at that time of year, any place in Spain would be fine, so it doesn't matter in that regard. It's what you want to do, I see no impediments due to it being October anywhere, at least definitely not the places you name. I think it could be different up on the Atlantic coast. Of course, the sea temperature may be cooler than you want for swimming, if that is your goal. But it is still very pleasant or even hot in Barcelona in early October, if that is your big concern (that Barcelona is a lot farther north than the other two). I know because I was just there last year at that time, and it could still be up to 85-90F in the day time, but it was pretty nice.

I disagree w/above posters! I was in Madrid, San Sebastian and Santiago de Compostela. In Oct/Nov it was cold and rainy pretty much the entire time-a couple of sunny but cool days in Madrid! When I say rain, in the north, it just poured!
I'm off again this year but this time I've moved my trip to Sept/Oct.

This is the perfect time to visit Andalucia which is blazing hot in the summer. I'd go to Madrid, spend a couple of days there, and then head south to Granada, Cordoba, Seville, and perhaps Malaga. Skip the north which can be very rainy, as someone said. Enjoy !

Generally "Green Spain" (the north west coast) should be considered wetter than the rest of Spain during the winter especially.

Bedar gave you some great advice.

thanks so much to all of you!!!

DO you know that weather is totally unpredictable. So what some one had during there last visit may not be fond this year.
Someone who is in city X and someone in city Y which less than an hours drive away can have different weather too.
In Spain, unlike cricket, you will find rain does not stop play.

We were there the first three weeks of October--Barcelona, Madrid, Avila, Salamanca, Segovia, Sevilla, Granada. Beautiful weather the whole time.

I'd expect nice weather in October but wouldn't expect it in November. For all I know, it might be fine in November, but I wouldn't count on it.