Octopus Think

26 October 2026

Now in beta: Tortoise Forecast, our weather app for runners

by Sarah

Find the best time to run—for free!—and help us build a great app.

Matt and I are both total run-nuts, and we love to run outside. Trouble is, weather apps don’t really help you contextualise what the forecast actually means for your run. Is it going to feel super hot at 19°C (66°F for those of you who haven’t adopted the metric system)? Does that rain icon mean a refreshing drizzle or a total downpour? How many layers do I need to wear?

So we got really, really nerdy about weather, and we built the app we wanted: Tortoise Forecast, the weather app for runners.

The Tortoise Forecast logo, a tortoise wearing a headband, and the tagline “The best running is outside”, beside an iPhone showing Tokyo at dusk, scoring 9, Ideal.

Want to give it a spin? Join our beta!

What it does

Your weather app tells you the temperature. We tell you what that actually means, and when is the best time to head out.

A score for every hour. Every hour gets a score from 1 to 10 for how nice it’ll be to run in. That number is based on our years of experience and a whole lot of obsessive research—temperature, humidity, wind, rain, UV, air quality, and active weather alerts—and adjusted for what’s going to impact your run most. We’re continually updating our algorithm based on feedback.

The Now screen for Santiago on a clear, starry night, scoring 10, Dreamy, beside three run scores: 9 Ideal, 5 Meh in the snow, and 2 Terrible in hot, humid weather.

The best times to run. In addition to the hour-by-hour breakdown, we tell you when the best times to head out are for each day.

Great running weather, but very hot in the afternoon: best time to run 4:00 to 8:00, with the temperature climbing from 14°C to 33°C, beside an hour-by-hour list of temperatures and run scores.

Details you care about. Hour-by-hour charts for temperature, wind, and rain. A minute-by-minute rain chart for the upcoming hour. Dew point, UV, and air quality. How long you have until there’s no more light. Oh, and whether that sunset is going to be worth waiting a little for. ☺️

Two iPhones showing the Now screen in Tortoise Forecast: Nairobi in heavy rain, scoring 7, Good, with a minute-by-minute rain chart; and Tokyo at dusk, scoring 9, Ideal.

Today, tomorrow, and the week ahead. Plan your runs in advance with detailed forecasts for the week.

Two minutes until sunset with last light at 21:35, beside the forecasts for today, okay running weather with an afternoon thunderstorm, and tomorrow, great running weather.

Rate your runs. Connect Apple Health to rate your runs and log how the weather felt. Those ratings will help us make more relevant recommendations in the future.

No snooping. Your data stays on your devices and syncs through iCloud. No analytics, no tracking, nothing about you stored on our servers. We’re not interested in spying on you.

Coming soon

We’ve been working on this for a while, but we have a whole lot more in the pipeline:

  • Personalised recommendations
  • Outfit ideas
  • Home screen widget
  • An Apple Watch app

We’re also full of ideas for other running apps, so expect more in this space.

Join the beta

  • It’s free. Everything, including the features that will eventually be paid upgrades, is free during the beta.
  • You need iOS 18.5 or later. We’re using Apple’s TestFlight to run the beta. It takes a minute to sign up and walks you through the process.
  • We ❤️ feedback! Send us an email, come chat in our Discord, or send screenshots straight from the app through TestFlight. We read absolutely everything and we use your feedback to shape the direction of the app.

Get beta access →

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