Carols said:
I think it was because they started earlier this year and wanted to stay in the cooler part of the country
Pentacycle said:
Idd, Southern Spain has an average max temperature of 35-40 °C atm.
It was 40º at the stage finish in Bilbao last year, and not far off that in Gasteiz the next day. I think they could have got away with going to the south, but given the earlier start it would have made more sense to go there at the end of the race than the start.
One of the main reasons for this (and for why the route is what it is) is the same as why the Volta a Portugal routes are what they are... there is more support for the sport in the north of the country. People commented last year on some of the early stages through Andalucía and especially the transitional stages heading northwards that there were very few fans along the routes - a decent amount at stage finishes, but lacking the atmosphere along the roads.
The north of the country is more densely populated and is more generally receptive to the sport, so staying north, while disappointing in that I'd like to see a more balanced route and a route that justifies the tag of being a Tour of a country, means the race may not be as swelteringly hot (which may discourage participation), and then even if it IS, it takes place in front of more people who are more willing to suffer the conditions to see the race.