Which set of dates to pick for a trip Andalusia?

Andalusia is generally warmer than Madrid. I've only been in February, and it was generally warm enough to eat outside wearing a jacket. I wouldn't worry about being too cold in October, I'd worry more about being too hot in September. There will probably be crowds in some places whenever you go. Be sure to buy your Alhambra tickets well in advance, they always sell out.

Starting in Madrid in late Sep/early Oct makes more sense from a weather perspective, but ten days makes no real difference....Madrid (2 nights) > Granada (2 nights) > Seville (3 nights) > Cordoba (1 night) > Malaga (2nights)

The later the better IMO. The later part of October will be much more temperate. The two weeks we spent there the first of October were very warm. We used air conditioning every place we went. The evenings also stayed warm. I don't remember even needing a jacket. The other advantage to going a little later is the possibility of fewer tourists.

I should have added that due to flight arrangements, we must fly into Malaga and out of Madrid.
Deciding between Sept and Oct, I keep seeing that September might be too hot and October might be a little wet? I checked historical data for the weather at this time of year, and it seems that there are more rainy days in October (especially in Granada? I think it says 9 rainy days vs 2 in September). Of course every year is different, but I feel like goldilocks ... I want to find just the right timing :)

I was in Madrid in 2009 from 22-26 October. I remember I carried a sweater every day, but never put it on, feeling quite comfortable in long shirt sleeves. It felt a little humid, and of course evenings were cooler.
It's the average max temps in October of 24/21/25/26/21 respectively that would sway me, rather than the possibility of rain. I would choose 7-17 Oct if I had to.

Oct 7 at a minimum. We home base out of malaga.

Anna,
I think any of your October dates would give you better weather than September when it may still be too hot in Andalucía.

My mom & I traveled to Andalucía last October ( 3rd -23rd) & we had some warm days (80's, even 90's) & a couple of rainy days.

When in Toledo, at the end of our trip, it was much cooler (mid 50's/ low 60's) & we did need a jacket & an umbrella.

One never knows what the weather will be like...

In terms of crowds, I thought we'd not have to deal with crowds, but we did encounter them, especially in Granada & Toledo.

Since Sevilla is a much larger city, we didn't notice the crowds as much.

Córdoba's main sites get very crowded as well because there are many tour buses that arrive there every morning & depart in the late afternoon.

We enjoyed spending a few days in all the cities we visited, especially in the mornings & evenings before/after the day trippers arrived/left.

Do take Chani's advice: Book your Alhambra tickets way in advance.

Enjoy your trip!

Edit: Since you've visited Madrid before, you may consider staying in Toledo this time-- one of my favorite cities in Spain thus far :-)

Thank you all for the input! I've been checking http://www.wunderground.com website that has a lot of useful data...and yes, indeed, each year is slightly different than the other. I remember being in Madird Sept 21-26th 2014, and looking at pictures I see us wearing long sleeves and cardigans in the evenings, that's the type of weather I like. I think for now (work schedule permitting) we'll be trying either Oct 7th or Sept 30th departure for Malaga.

Priscilla, I, too, loved Toledo which we visited as a day trip from Madrid ;)

Hello Anna,

I go to Spain every year in October. I have visited throughout the country and spent time from Valencia to the Basque area and from Catalonia to Andalusia, as well as in Madrid and Barcelona. I have found the weather in all of these areas to be beautiful at that time of year. While it is true that Spain is never really tourist free, October typically has many fewer than other times of the year and lines, if there are any at the most popular sites, are quite short and fast moving.

Jack

Thank you Jack! Aiming for the beginning of October right now.