It’s always important to be ready for any kind of weather, all year round. Knowing what to wear is more important then the amount of layers you wear. Quality over quantity!
During winter, it’s important to look at the weather every couple of hours, specially if you are driving out of the city, to make sure you wont get stuck in a snowstorm. During summer you could get rainstorms, but these aren’t as frequent or as dangerous.
Because the weather can change so fast its important to have a flexible plan, especially during the winter months; it is possible that you won’t be able to do some things because of weather.
When to go to Iceland is the most common question on people’s minds when planing their trip. Which is better? Winter? Summer? This question is impossible to answer because it’s like 2 different countries; the weather has that much effect. Do you want to be 100% sure you can drive the ring road? Choose summer. The weather is much calmer and you get 24 hours of sunlight. Do you want the chance to see the northern lights? Choose winter. There’s only 3 hours of sunlight in December, which makes it more likely to see them.