<p>This is an (annoying) artefact of BBC weather forecasts, and not an actual feature of the weather.</p>
<p>At low wind speeds, the speed shown is the expected average speed.</p>
<p>At higher wind speeds, the speed shown is the maximum expected gust.</p>
<p>It changes over when the maximum expected gust is 40 mph (not knots). You can tell the difference because average wind speeds have a white background, and gusts have a black background:</p>
<p><a href="https://i.sstatic.net/DdBzB.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/DdBzB.png" alt="Wind speed transitioning from average to guests on BBC forecast" /></a></p>
<p>There is a little bit of explanation about half way down this page: <a href="https://www.bbc.com/weather/about/17185651" rel="nofollow noreferrer">https://www.bbc.com/weather/about/17185651</a></p>

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2019-10-15T20:30:05.620Z
Ahh! That makes sense now of course. Thanks.
Calanus
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2023-07-17T12:53:59.917Z
@philip C thanks for editing this screenshot in!
Semidiurnal Simon
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2023-07-17T12:59:44.330Z
@SemidiurnalSimon No problem - I was looking for the answer you gave because I noticed it on the forecast that day :P
Philip C
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2019-10-10T17:09:06.430Z
2023-07-15T11:35:13.363Z
2023-07-15T11:35:13.363Z
Semidiurnal Simon
<p>Looking at the BBC weather forecasts I've often noticed that strong winds will often be over 40 knots (for the UK at least). Most of the time (nearly always) the wind will jump from 18-22 knots to over 40 from one hour's forecast to the next. I don't often ever see wind speeds in the high 20s or 30s. Why is this the case? I looked at the Weibull distribution but this doesn't seem to apply.</p>

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2019-10-10T11:21:24.497Z
Link to *Weibull distrubition* please... Also, your term *jump* needs a timespan - it makes quite a difference if the increase is in 5 minutes or 1 hour. Please [edit] the question.
Jan Doggen
<wind>
Why do wind speeds often jump from 20 knots to 40 knots
Robin Clark
# Why do wind speeds often jump from 20 knots to 40 knots

(Asked by: username_0 on 2019-10-10)

Looking at the BBC weather forecasts I've often noticed that strong winds will often be over 40 knots (for the UK at least). Most of the time (nearly always) the wind will jump from 18-22 knots to over 40 from one hour's forecast to the next. I don't often ever see wind speeds in the high 20s or 30s. Why is this the case? I looked at the Weibull distribution but this doesn't seem to apply.

**Tags:** wind

> **Comments:**
> **username_1**: Link to *Weibull distrubition* please... Also, your term *jump* needs a timespan - it makes quite a difference if the increase is in 5 minutes or 1 hour. Please [edit] the question.  

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## 1 answers

### Answer by username_2 on 2019-10-10. Score: 7 | Accepted answer

This is an (annoying) artefact of BBC weather forecasts, and not an actual feature of the weather.

At low wind speeds, the speed shown is the expected average speed.

At higher wind speeds, the speed shown is the maximum expected gust.

It changes over when the maximum expected gust is 40 mph (not knots). You can tell the difference because average wind speeds have a white background, and gusts have a black background:

[![Wind speed transitioning from average to guests on BBC forecast](https://i.sstatic.net/DdBzB.png)](https://i.sstatic.net/DdBzB.png)

There is a little bit of explanation about half way down this page: <https://www.bbc.com/weather/about/17185651>

> **Comments:**
> **username_3**: Ahh! That makes sense now of course. Thanks.  
> **username_2**: @username_4 C thanks for editing this screenshot in!  
> **username_4**: @username_2 No problem - I was looking for the answer you gave because I noticed it on the forecast that day :P  

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