Sicily in October

We are going early October. I hear it is what we call in Colorado Mud Season. Can be blustery and raining, so it may feel colder than it actually is.

We have been to Sicily twice in mid to late October. There were a few big rain storms so bring a rain jacket but mostly nice weather. The only place we encountered mud was for a few hours at The Valley of the Temples but you could walk around it.
Looking at our photos, for daytime my husband wore shorts and short sleeved shirts, some long sleeved and I wore capris and short sleeved tees, occassionally a long sleeved one. We’ve loved our trips to Sicily.
Great lavenderia in Ortigia: on a side street to the right after you cross the bridge from Siracusa. Wash, dry, fold, fast. Not expensive. 9€ per load.
Lavenderia Ad Acqua Ortigia
Via dei Mille,25
Ortigia
8:30-1:30, 3:30-7:00

We were there three weeks very end of September to mid end October 2016 and 2017, 2016 was hot and sunny the whole time, 2017 a couple of days of heavy rain, but generally nice. Both times I swam several times, for example :
https://slowtravelitalyspain.blogspot.com/2019/02/west-coast-sicily-day-9-san-vito-lo.html?m=1

To get a good picture of the range of weather you may experience, I highly recommend looking at actual day-by-day historical weather stats for October 2018, October 2017, etc. They are available on timeanddate.com. I've linked to Palermo for October 2018, but you should probably check a couple of other locations. Choose places you're going--maybe Siracusa and one of the inland towns in the center of the island (Piazza Armerina? Enna? Caltagirone?). Definitely take a look at more than one year.

I am not knowledgeable about how the weather in Sicily might vary from location to location.

Can’t speak to the end of October since I was there late September and short sleeves were the norm most days. A light jacket was needed on a couple evenings. We only had rain one day.

parkbooker, your hotel should be able to direct you to a lavanderia or do it for you for a price. We were just in Siracusa two weeks ago on the RS tour (staying in Orytigia) and there was one that took care of our laundry (one full bag 15€) no problem.

I was there last year in mid-October. Except for one day of rain, I would say the weather was perfect. Temps were in the 60s - 70s. Somedays I wore a polo shirt, while other I wore a polo and light jacket. It does get cooler if you go up into the mountains.

On average you should expect mildly warm temperatures during the day with coolish temperatures at night and early mornings. A light jacket will do for the evenings. Rain, even heavy downpour, is a likely possibility at least for some of your stay, so carry a travel umbrella or other rain gear if the forecast calls for it.