San Francisco has very changeable weather in our experience, and is the kind of place it is always worth carrying a couple of layers with you when you set out for the day. Always pack a warm layer and a waterproof with you when you go to San Francisco, no matter what time of year it is. There can also be big differences in weather in a small area. For example, downtown can be blanketed in fog when a few miles inland can sometimes be bathed in glorious sunshine. Consequently, if you are there for several days you can often plan your days activity according to the weather and make the most of the variability.

The very best time of year to visit is September and October when you are most likely to get warm, sunny, dry days and mild nights. It can get much hotter this time of year than it does in the summer, so if you are someone who really does not enjoy the heat, spring may be better.

Spring is probably the next best time to go to San Francisco. March, April and May tend to be dry and sunny months, without the heat you can get in the autumn.

San Francisco summers be cool, damp and foggy. The foggy marine layer usually disappears during the afternoon and once the sun comes up you will feel the temperature immediately start to rise. If you need to travel during the school holidays, leaving your trip until as late in August as possible is your best bet for maximum sunshine. It is also a great time of year for photographers, as there is often fog around in the Bay area. The sun glinting off a fog bank can make for some really dramatic scenes.

Winter is San Francisco is normally relatively mild, but can be very damp.

For more information on average temperatures and rainfall, we like weather.com.