We’ve had wind displays on mobile for ages — those hypnotic little wind particles swirling around like they’re auditioning for a weather-themed screensaver. But now we’re bringing something new (and pointier) to the web: wind direction arrows.

If you’ve ever stared at a pressure map thinking, “Cool, but which way is this thing actually moving?” — this is your new favorite feature. The short answer: arrows. The long answer: Well, keep reading.

From Data to Direction

It starts with our two-component data sets. These could be lots of things, like tides or… other stuff, but they’re mostly wind. For example, here’s GFS 10m winds in Canada today.

See that low-pressure area in the middle? We can guess that it’s spinning just by the shape, but wouldn’t it be great to know for sure? And in which direction (you can probably guess from the shape, but humor me)?

Well, that’s what wind direction arrows are good for!

Wow, that sure is clear! Thanks, arrows!

This all animates, too. Blink your eyes really fast to simulate. Or update to the latest Terrier, if you’re one of our customers.

How to Add Wind Direction Arrows in Terrier

These arrows are optional in the wind display. They’re pretty easy to use, just add this setting to your startLayer call.

The cutoff and min/max speed are in m/s. We’ll scale between the pixel sizes given, and we use layout to drop down that grid of arrows, which will update every time you move. We interpolate between the colors based on the speed, and we might want to make that a bit more flexible in the future. We’ll see how people use it.

You can also add an optional PNG file as an ‘image’. We’ll use our made-up arrow if not.

The Tech Behind the Arrows

These are implemented with a combination of internal markers and a custom WebGL shader. That makes them incredibly cheap to render. Since all of this is within Terrier, we can overlay these on every supported web map toolkit.

Why Wind Direction Arrows Matter

Sure, you could squint at wind particles and make an educated guess about what’s happening. But why guess when you can know instantly? Wind direction arrows turn raw wind data into something obvious, readable, and surprisingly fun to watch.

Whether you’re building weather dashboards, visualizing aviation patterns, or making sure nobody’s beach umbrella takes flight, this is a small but mighty upgrade. We can’t wait to see how you use it, and we’ve got plenty more features like this in the works.