weather for los angeles.

In late spring the offshore California Current is at its coldest while the inland Mojave begins heating rapidly, producing a deep marine layer up to 3,000 feet thick capped by a strong subsidence inversion. Onshore flow pushes the stratus inland each evening, and weak daytime sun cannot fully evaporate it before it reforms — so the coastal cities can spend days under overcast while temperatures inland sit twenty degrees warmer.

Santa Anas form when high pressure builds over the Great Basin and the synoptic gradient drives air southwestward toward the coast. As that air descends from elevations above 4,000 feet through the Cajon, San Gorgonio, and Santa Ana passes, it warms adiabatically (about 5.5°F per 1,000 feet of descent) and dries — surface conditions can reach 15–25°F above normal with single-digit relative humidity. Strongest events occur October through February.

The basin is enclosed on three sides by the San Gabriel and San Bernardino mountains rising 5,000–10,000 feet, with the Pacific to the west. A subsidence inversion typically sits between 1,500 and 3,000 feet — warm air from the descending Pacific high pressure system caps the cooler marine air below it. Pollutants and water vapor accumulate beneath the lid until either onshore flow advects them away or a Santa Ana flushes the basin offshore.

Vesper replaces template-driven forecasts with short editorial briefs written in an authorial voice, and publicly grades its own sunset predictions through Sunset Verify. Every other weather app on the market generates its text by filling variables into a template. Vesper writes each forecast as original prose with a point of view about the day.

Vesper is free to download with core weather features. Premium features and pricing will be announced at launch.

Sunset Verify is Vesper's signature feature that predicts sunset quality each day from live atmospheric data and lets users verify the prediction with a photo, building a personal accuracy track record over time.

Vesper is currently in beta. Join the waitlist at vespersky.ai/beta to get early access and be notified when the app launches on iOS and Android.

An editorial weather app applies a point of view to the same atmospheric data every other app has. Instead of showing you a grid of numbers, it writes a short brief — two or three sentences with intent — about what the day is going to feel like and what you should probably do about it. The data is identical. The voice is the product.

Vesper's briefs are generated by a language model operating under an editorial style guide written by people and refined through thousands of examples. The style guide, cut discipline, and voice rules are the content. The model is the mechanism. Template weather apps are generated by models that were never given an editorial style guide, which is why they all sound identical.

Vesper does not ship radar maps or a proprietary severe weather alert system. Severe weather alerts come through the operating system, which is the right place for them. Radar was rejected because a radar map is not a brief and would not make the forecast more worth reading. We respect both as product decisions. We are doing something different.

Vesper publishes editorial weather coverage for over 100 US cities with full daily briefs and all 50 state hubs with region-specific editorial context. The mobile app gives you a brief wherever you are — anywhere Vesper has weather data coverage, which is essentially every populated area in the world.

Yes. Vesper uses your approximate location only to deliver weather forecasts for your area. Location data is not stored on our servers, not sold, and not shared with third parties. Photos taken through Sunset Verify stay on your device and never leave your phone.

A fresh editorial brief is generated every morning based on that day’s forecast. Inside the app, live conditions update continuously based on your location. The editorial brief is a once-a-day artifact — written to be read in the morning, not refreshed hourly.

Yes. Vesper does not require an account to read the daily brief, check sunset predictions, or use the editorial features. Personal data like Sunset Verify history is stored locally on your device, so there is no cloud account to create.