My husband and I have decided to visit Belgium (mainly Bruges) at the end of October. But we are doubtful as to how cold (chilly and unsettled) the weather might be. In my country (middle East), it is pleasantly cold at the time and we are not accustomed to chilly weather since the lowest temp in Winter would be above 7(c).
Weather in that part of Belgium is always mild but mostly colder than you are used to. It can rain any day of the year but it will not rain every day and most of the time it will not rain all day either.
Temperatures range from -10 to +30 C, but in October it is most likely to be in the +5 to +15 range. How warm it will be depends on the actual weather and weather in Belgium is hard to predict more than 3 days ahead.
Best take clothes for a range of temperatures and layer them, have a waterproof outer layer and plan on using it instead of an umbrella.
Mostly rain come with cold winds and a coat or jacket that is pretty much waterproof over a warm layer will keep you much warmer and rain in wind can come from the side rather than above.
But even though the weather can be nasty, it is worth to see Bruges. See the weather as part of the experience. Most of the time it is nice weather and the visit will be great.