San Francisco's weather is really unique in the summer.

Most first-time visitors to SF think, "It's California, so it must be hot," and are surprised when they only pack short sleeves.

I also wondered why it was so cold in the summer at first. Even in July and August, you see plenty of people wearing thick hoodies or jackets.

The reason is that San Francisco has a Mediterranean climate, but it's quite different from the California weather we usually think of.

The average annual temperature is about 14℃, with little variation throughout the seasons. Look at the temperature I posted above. That's the weather and temperature from July 25 to August 1, 2026.

Anyway, it rarely drops below freezing in winter, and it's uncommon for summer days to exceed 30℃.

As a result, San Francisco has one of the highest percentages of homes without air conditioning among major U.S. cities.

According to research, it's reported that over 60-70% of homes do not have central air conditioning.

Here, heating is considered a more important facility. However, recently, with the increase in heat waves, the installation of air conditioning is gradually rising, especially in new condos and apartments, but in older homes, it's still common to live without air conditioning.

Also, you can't talk about San Francisco without mentioning the fog.

Locally, this fog is so famous that it's nicknamed 'Karl the Fog.'

The fog forms when the cold California current meets warm air, and it's not an exaggeration to say it appears almost every day, especially between June and August.

Interestingly, the summer, when the most tourists visit, is actually the coolest season. Many days, even during the day, the temperature stays around 13-17℃, and when the wind blows, it feels even colder.

So, in San Francisco, "layering" is a way of life. Mornings can be chilly due to the fog, but by lunchtime, the sun comes out and it warms up, and often, by late afternoon, the wind and fog return.

You can often see locals wearing a thin t-shirt with a hoodie or fleece and a windbreaker on top. If you only bring short sleeves thinking it's summer, you're likely to regret it.

Even within San Francisco, the weather varies by neighborhood. Areas close to the ocean, like Golden Gate Park, Sunset, and Richmond, often have lingering fog and many cool days.

In contrast, areas like Mission District, Potrero Hill, and Bayview get plenty of sunshine and are a few degrees warmer, leading locals to often say, "Mission is warm." This is why weather is a consideration when looking for a place to live.

If Korean visitors are planning a trip or move to San Francisco, there's one thing to remember. Set aside the thought that "It's California, so it must be hot." I recommend packing a light jacket or hoodie and a windbreaker even in the summer.