Is SoCal really sunny?
Visualizing 365 days of NOAA GOES-16 satellite imagery
Southern California is often marketed as a place with perfect weather. But for the millions of people living along the coast, it is frequently cloudy. To answer the question "Is SoCal really sunny?", we analyzed the actual weather patterns by processing 365 days of NOAA GOES-16 satellite imagery from 2023.
Hover any day to see the satellite view. Toggle modes below to compare times.
This is the view from space at 8:00 AM each day. Contrary to the stereotype, perfectly clear mornings are rare. 55.07% of mornings in 2023 (201 out of 365 days) had over 50% cloud cover.
The year started with heavy storms. January through March 2023 saw historic rainfall and thick, persistent clouds.
In spring, the pattern changes. The marine layer forms more often, covering the coast in low clouds.
By June, the marine layer is thickest. For people living near the coast, the sun is often blocked for weeks at a time.
Switching to 2:00 PM shows a different picture. As the land heats up, the clouds usually evaporate. However, clouds still lingered in the afternoon 47.95% of the time in 2023.
True summer comes late. September and October are often the clearest, hottest months as dry desert air pushes the clouds away.
The time of day is just as important as the season. Try comparing the morning and afternoon views to see how the cloud patterns change each day.
The yearly view shows us the overall trend, but it's better to see the daily reality more closely. To capture the day-to-day experience, we measured the daily average cloud fraction—the percentage of pixels classified as cloudy—specifically for the coastal region (32°N to 35°N). This tool lets you explore those daily patterns with a closer look.
Drag the scrubber to observe the daily cloud patterns across 2023, or play time-lapse videos to see how cloud cover changed over the course of a year.
Tip: Click the "Deep Dive" button to explore more detailed cloud patterns in selected days.
From the above sections, you might have noticed a weird pattern of foggy mornings and sunny afternoons that
happens during late Spring and early Summer, from mid May to almost the end of August. This persistent
pattern is most commonly known as "June Gloom", while also has other colloquialisms such as
"Graypril", "May Gray", "No-Sky July", and
"Fogust".
The satellite data shows us
what it looks like, but to understand why it happens (what's marine layer??), we have to
look at the physics.
Usually, air gets cooler as you go higher up. This allows clouds to rise easily and fade away into the atmosphere.
In June, a layer of warm air sits on top of the cool ocean air. This warm layer acts like a cap (or "inversion") that holds the cool, moist air down.
Cool ocean breezes push clouds inland against the mountains. Because they are stuck beneath the warm air layer, the fog forms a thick sheet over the coast.
When the sun rises, it warms the ground. This heat mixes the air and causes the fog to evaporate (or "burn off").
Try it: Scrub the slider to clear the marine layer.
Having examined the daily rhythms of the cloud cover through satellite imagery, we now turn to its long-term impact. To quantify how this persistent gloominess shapes the Southern California summer, we used analyzed 24 years of CMIP6 historical climate models (1990-2014), and 85 years of CMIP6 future climate models (2015-2100)
Explore how key climate variables (Clouds, Temperature, Wind Speed, Solar Radiation, and Air Pressure) are distributed seasonally and how they evolve from Historical trends to Future scenarios (CMIP6).
These regional averages show the general pattern, but the weather changes drastically depending on where you are. We used these long-term climate averages to build a ranking model for every city. Use the tool below to find the location that matches your specific preferences.
See the latest 4-hour cloud cover conditions in real-time, updated every 30 minutes.
GOES-18 GeoColor Satellite Loop (Pacific Southwest Sector) • Data courtesy of NOAA NESDIS STAR