You open a forecast and see wind at 25 km/h with gusts of 50 km/h. These are not conflicting predictions: one figure summarises the wind over an interval and the other describes its peaks. To understand the conditions, you need both, together with the location, time and units.
This is an educational guide, not a report of current warnings or a forecast for a particular event. All figures in the examples are hypothetical.
What is the difference between mean wind and a gust?
Mean wind is an average; a gust is a brief increase in speed. In Met Office measurements, gust speed is the highest three-second average.
The interval within which that maximum is selected is a separate matter. In AEMET’s hourly observations, wind refers to the preceding ten minutes and maximum gust to the preceding sixty minutes. Do not confuse the peak’s duration with the reporting period.
A 50 km/h gust therefore does not mean wind at 50 throughout the hour. Nor does it mean exactly 25 the rest of the time. The average alone does not describe every rise and fall.
An example comparing two forecasts
| Hypothetical example | Mean wind | Maximum gust |
|---|---|---|
| Situation A | 25 km/h | 50 km/h |
| Situation B | 40 km/h | 50 km/h |
The maximum is identical, but B’s average is 15 km/h higher. Looking only at gusts would hide that difference. Looking only at A’s average would hide the fact that its peaks reach twice that value.
The ratio, 50 ÷ 25 = 2, is used here to compare numbers, not to calculate damage or set a safety limit. These figures also do not reveal how many gusts there will be, their exact timing or how long each will last. Do not turn a summary table into a sequence it does not provide.
Units and direction: two quick checks
Before comparing apps, use the same units: 1 m/s equals 3.6 km/h. Thus 10 m/s is 36 km/h, and 15 m/s is 54 km/h. A value of 15 m/s is greater than 40 km/h, even though 15 looks like the smaller number.
The named direction indicates origin: a westerly comes from the west. Check the service’s legend to interpret arrows; the Met Office explains its symbols and periods. Do not guess the meaning of an isolated arrow.
How to check the forecast before going out
- Read the label: mean wind, forecast gust or observed maximum? A past measurement is not a forecast.
- Check the interval: do not compare a daily gust with an hourly average as if they summarised the same thing.
- Compare the same location: note the town, site or station; do not unknowingly mix figures from different places.
- Cover the whole activity: check the return period as well as departure.
- Open the official warning: check the hazard, area, validity and applicable instructions.
For example, if you plan a walk from 10:00 to 13:00, a screenshot showing 10:00 does not tell you what is expected over all three hours. This is a reading check, not permission to undertake the activity.
At what speed does wind become dangerous?
No single figure guarantees safety for every activity. AEMET distinguishes weather hazard from risk, which also depends on exposure and vulnerability. Read its warning guidance and current warnings for Spain.
In strong winds, Civil Protection advises securing windows and loose objects and keeping away from items that could fall. Mazarrón Town Council reproduces this official advice. Follow local instructions.
The practical lesson is simple: do not choose between mean wind and gusts. Read both and retain their context. A number without a unit, period or location is incomplete information.
You can also read our guide to the colours of weather warnings in Spain.
Sources checked on 3 September 2026. Cover: AI-generated illustration, not a depiction of a real event. AEMET and Civil Protection links are in Spanish.