The weather in Boulder and Madrid are remarkably similar, which is why I think I haven't started feeling homesick. I still feel like I'm at home in a lot of ways, and the physical adjustment to this city has been so minimal.
You just about count on a sunny day here, in fact today is the first rainy day we've had since we got here. The sun isn't overwhelming here either, since the air is so dry your sweat actually evaporates, and is very effective at keeping you cool. Madrid also has the amazing feature of being a few degrees cooler in the shade versus direct sun.
If you look at the geography of the two cities, they are about as similar as you can get for being on different continents. Both are in the middle of their countries, at the foot of mountains and are in a rain shadow, both are high elevation, and both are at 40 degrees north latitude. Ben really likes the geographical similarities because the amount of convergent evolution between the two places is outrageous. The soil is even similar in both countries, I'm fairly certain any plant that thrives in Colorado could also thrive here.
One of the nice features of the weather in both cities, is that there is generally a breeze going. This prevents that stagnant air you can get in other cities. Sometimes it can be pretty strong here, but most days it is just enough to be refreshing.
A rainy day in Madrid seems to be an excuse to cozy up in a cafe or stay at home. It feels so sleepy, and the normal hustle of the city has slowed to a crawl. It's a welcome change, and I plan to read, study Spanish, and cook delicious dinner.