I've gone through 2 sim years in Tartosa and I can hardly tell the difference between summer and winter. My sims are generally in their everyday wear all year. I've yet to see a day that required hot weather and only a few were chilly enough to wear cold weather.
They can get chilly while swimming but only need to put on everyday wear to warm up.
It rains I'm guessing 50 to 60% of the time and stays overcast another 20 so I really only enjoy sunny days a relative 30 ish percent of the year. It doesn't have the feel of a sunny/ hot beach world (even in summer) but kinda soggy and tepid year round. My sims lot is covered in mud puddles quite often from the amount of rain and a few times these giant puddles formed in the home as well when the rain was enough to cause mud puddles. No broken appliances or pets caused these random puddles indoors.
