What Alpenglow is

Alpenglow is a sunrise and sunset forecast app for photographers and anyone who pays attention to the sky. It predicts the quality of the upcoming sunrise or sunset for your location — not just the time, but how good it's likely to look — and sends a heads-up so you don't miss the good ones.

Today the app runs on iPhone, iPad, Mac, Apple Watch, Apple TV, Vision Pro, Android, and TRMNL, with widgets, share sheets, and Forecast Maps that let you scan conditions across an area or plan a shoot up to seven days out.

The story

Alpenglow first launched on the App Store ten years ago. Back then it didn't even include sunrise or sunset times. The original idea was simpler: people would rate the sky after sunrise or sunset, and those ratings would power alerts for others nearby. It had a chicken-and-egg problem early on, as anything community-powered does, and over the years it grew into something different — an app that uses real weather model data to forecast the colour and quality of the sky before it happens.

For nearly its entire lifetime, those forecasts were powered by SunsetWX, which generates predictions from the NAM and GFS weather models. SunsetWX has been a major contributor to Alpenglow's success, and I'm incredibly thankful for the work they've done.

Building Alpenglow's own forecast model

Any app that depends on a single external service is only as reliable as that service. Over the last few years I've been working on Alpenglow's own forecast model behind the scenes, partly for resilience and partly because owning the model unlocks features that simply weren't possible before.

That model went live earlier this year, after one Saturday night when SunsetWX briefly went offline and I flipped the switch sooner than I'd planned. It's now what powers Forecast Maps, the 7-day forecast horizon, and a lot of the other features that shipped with the 10-year update — and it's the only forecast source Alpenglow uses today.

Who builds it

I'm Andrew Yates, an iOS Engineer based in San Francisco. My day job is at Buffer; Alpenglow is a long-running side project I've been building for ten years alongside that work.

I also build Starglow, a companion app for stargazing forecasts, and write occasional posts on the Alpenglow blog about new features, the forecast model, and what's coming next.

How to get in touch

The fastest way to reach me about the app is via the contact form. For press and media enquiries, the press kit has logos, screenshots, and background.

By the numbers

10 years on the App Store (launched 2016)
1.6M+ downloads
10,000+ App Store ratings, average 4.5 / 5
Available on iOS, iPadOS, macOS, watchOS, tvOS, visionOS, Android, and TRMNL