Pro Weather· Updated
What Is a Wind Rose and How to Read One
If you have looked at a weather station website, you have probably seen a circular chart with colored petals radiating from the center. That is a wind rose, and it is one of the most efficient ways to visualize wind patterns at a glance.
This guide explains what a wind rose shows, how to read one step by step, and what your own rose can tell you about your local microclimate.
What does a wind rose show?
A wind rose shows how often the wind blows from each compass direction, and how strong it typically is when it does, over a chosen period of time. Each petal points in the direction the wind comes from; petal length shows frequency, and the colored segments within it show wind speed ranges.
It answers two questions no single number can: "where does my wind usually come from?" and "how strong is it when it blows from there?" An average wind speed hides both.
Each petal or spoke represents a compass direction. Wind roses use either 8 directions (N, NE, E, SE, S, SW, W, NW) or 16 for finer granularity, and can cover any period — a day, a month, a season, or years. Every petal is built from thousands of individual readings taken by your station's wind cups and vane; if you are curious about the hardware behind it, see how weather station sensors work.
How do you read a wind rose?
Read a wind rose from the center outward. Find the longest petal — that is your prevailing wind direction. Its length tells you what share of the time the wind arrives from there, and the color bands along it tell you how strong it usually is. The circle in the middle counts the calm periods.
In detail:
- The center of the circle represents calm conditions (very little or no wind).
- Each petal points outward in the direction the wind is coming from. A long petal pointing north means the wind frequently comes from the north — it does not mean the wind blows toward the north.
- The length of each petal shows how often the wind blows from that direction, relative to the other directions.
- The color of each segment within a petal shows the wind speed range for that direction. Colors almost always progress from light (gentle) to dark (strong).
The "from" convention in step 2 is the single most common reading mistake. Meteorologists name winds by their origin — a "southwesterly" comes from the southwest — and wind roses follow the same rule.
What do the colors on a wind rose mean?
The colors on a wind rose represent wind speed bands. Each petal is divided into stacked segments, one per band, and lighter colors almost always mean lighter wind. There is no universal standard scale, so always check the chart's legend — the exact speed ranges vary between websites and tools.
A common scheme looks like this:
| Typical color | Wind speed | What it feels like |
|---|---|---|
| Light blue or light green | 0–12 km/h | Calm to light breeze — leaves rustle |
| Teal or medium green | 12–28 km/h | Gentle to moderate breeze — flags extend |
| Orange or amber | 28–49 km/h | Fresh to strong breeze — umbrellas struggle |
| Red or dark red | 49+ km/h | Near gale and above — walking gets hard |
Reading length and color together is where the rose earns its keep: a long light-colored petal means frequent but gentle wind, while a short dark petal means wind from that direction is rare but fierce when it arrives.
What does reading a real wind rose look like?
Picture a year-long wind rose with one long petal pointing southwest, mostly orange and red, a shorter all-blue petal pointing northeast, and a small calm circle. Reading it: wind usually arrives from the southwest and arrives strong; northeasterly wind is occasional and gentle; genuinely calm hours are rare.
Now go one level deeper. That long, dark southwesterly petal tells you which side of the house takes the weather: it is the quadrant your storm damage, driving rain, and wind chill come from, and the direction a windbreak or fence should face. The short blue northeasterly petal might be a fair-weather pattern — in much of northwest Europe, for instance, northeasterlies often accompany dry high-pressure spells.
If one sector of the rose is nearly empty, ask why. It could be genuine terrain sheltering — a hill or forest upwind — or it could be your own building blocking the anemometer. Comparing a winter rose with a summer rose is equally revealing: many locations flip their prevailing direction with the seasons, and the rose makes the flip obvious in a way a table of numbers never will.
Why does a wind rose matter for weather station owners?
A wind rose turns months of individual wind readings into a pattern you can act on: which side of the garden needs a windbreak, when a sea breeze reliably kicks in, which quadrant storm winds arrive from, and whether a fence or building is quietly sheltering your anemometer.
After a few months of data, you might discover:
- Your prevailing wind shifts seasonally (northwesterly in winter, southwesterly in summer)
- Your location has a consistent daily sea breeze from a specific direction
- Storm winds always arrive from the same quadrant
- Certain directions are almost always calm, suggesting a local sheltering effect
That is directly useful for gardening (knowing where frost drainage and drying winds come from), sailing and kite flying, and simply understanding your microclimate. One caution: a wind rose is only as honest as the anemometer's placement. A mast below roof level or a nearby tree carves a permanent dent into one side of the rose — the station siting guide shows how to mount for clean wind data. A sticking wind vane skews it too, which is why an anemometer check is part of our weather station maintenance checklist.
How does Pro Weather build its wind rose?
Pro Weather builds its wind rose from the raw per-tick wind samples your Davis station records, rather than from hourly averages, so brief shifts and squall directions are preserved instead of averaged away. The rose updates automatically as new data arrives, and you can switch between an 8-point and a 16-point view.
Averaging is the quiet weakness of many wind rose implementations: a front passing through with a sharp wind shift gets smeared across two directions, and short-lived storm gust directions vanish entirely. Working from every recorded sample keeps those events in the picture.
If you have a Davis station with an anemometer, the data is already flowing. Start your site and watch your local wind patterns take shape — the rose fills in on its own from the day you connect.
Common questions
What is the calm circle on a wind rose?
The circle (or percentage figure) at the center represents the share of time when the wind was too light to have a meaningful direction — a nearly stationary vane just reports noise. Rather than scattering those readings across random petals, the chart pools them in the middle. A large calm circle usually means a sheltered site or a genuinely still climate.
Does a wind rose show gusts or average wind?
Almost always sustained wind, built from regular samples — not gusts. Gusts are brief spikes that stations record separately, and a rose built on them would exaggerate the strong color bands. The two numbers can differ by half or more in stormy weather, and the distinction matters more than most owners expect: see wind gusts vs sustained wind.
How much data do you need for a useful wind rose?
A few weeks of data is enough to reveal your prevailing direction, but a full year is needed before seasonal patterns show up honestly. A single day's rose is an anecdote — it describes one weather system, not your climate. The more samples behind the chart, the smoother and more trustworthy the petals become.
What is the difference between a wind rose and a compass rose?
A compass rose is the static direction symbol printed on maps and charts — it shows where north is and carries no data. A wind rose borrows that circular layout but fills it with measurements: how often, and how strongly, the wind actually blew from each direction at one location over a period of time.