There's a good saying 'there's no such thing as bad weather just wrong clothing'. A good or bad cycle can be solely determined not by the size of hill or how much singletrack there is but by wearing the right or wrong clothing.
There are lots of different types of clothing and shoes available for all different types of weather. Finding the right clothing combinations are very personal and will take a certain amount of time and experimentation. Try to avoid wearing cotton especially next to your skin, it doesn’t breathe very well and will get very sweaty or won’t dry quickly if it rains. Try different man made materials or merino wool base layers to find what works for you. Remember to take a warm layer and waterproof. Try bike shops, outdoor stores or online retailers.
It can be expensive trying different clothing options so why not ask the experts or friends/family for their recommendations.