Whether or not you get a tan has nothing to do with the temperature...it's about how much sun you get...which you shouldn't try to do without good sunblock...and you probably WON'T get as much of a tan/burn, because the earth is further from the sun than at any other time of the year.
You can get a tan even if the temperature is 0 degrees Celsius. For sun tan purposes the temperature does not matter - it the exposure to sunlight that is the only significant criterion. That's why some people get very bad sunburn on bright days even though it seems to be cool. Don't make the dangerous mistake of thinking that you must be hot to burn.
24C is considered quite warm in the UK. If we have more than a few days consecutively with temperatures at 24C or warmer then it's considered to be a Heat Wave. In Spain they are more used to warm temperatures. 30C is common in the south in the summer and 24C is pretty normal, even in October.
You'll be able to walk around in shorts and feel very warm and comfortable. The locals will wonder why you are "half naked" in temperatures that they consider to be cool.
You will most certainly tan, but still use good quality sun protection, 24C for Spain is hot, but on the Costa del Sol we have had temps this past 2 months of 38/44C, plus the fact it does also depend on how much heat you can take, either way you must take care.
24 Degrees Celsius is about 75 degrees Farenheit.
I'm going on holiday to Spain in October with my best friends, and the average temperature where we're going is 24 degrees C, and I'm wondering if that's hot enough to wear shorts and/or get a decent tan? I went when I was 11 in October and got an amazing tan, but that was 8 years ago and I'm sure it was a heatwave.
