<p>Doesn't appear to be great sources out there for some of this info!  (But then, that's what StackExchange has great promise in being!)</p>

<p>In the US, <a href="http://www.nws.noaa.gov/asos/pdfs/aum-toc.pdf" rel="nofollow noreferrer">this manual</a> for the official instrument setup, as well as this <a href="http://www.nws.noaa.gov/om/forms/resources/SFCTraining.pdf" rel="nofollow noreferrer">old manual</a> on how to take observations gives quite a bit of good detail on how wind observations are done...</p>

<p>In the US, <strong>wind speed is the most recent 2 minute average</strong>.  </p>

<p>A thorough explanation for gusts for ASOS, which is about as readable as syrup:</p>

<blockquote>
  <p>In the manual procedure, a gust is reported when an observer sees
  rapid fluctuations in sensor wind speed indications with a variation
  of 10 knots or more between peaks and lulls during the 10-minutes
  before the observation. The reported gust is taken from the maximum
  “instantaneous” wind  speed  observed  during  this  period.  The 
  average  2-minute  wind  is  used  to  report  wind  direction  and 
  wind speed.  Conceivably,  an  average  2-minute  wind  speed  as low 
  as  3  knots  (observed  in  the  last  minute)  may  be  reported
  with a gust of 10 knots (observed in the last 10 minutes).
  Observations of 5 knots with gusts of 10 to 15 knots, however, are the
  more common minimum values reported.</p>
  
  <p>The ASOS algorithm also relies on a 10-minute observation period to 
  determine gusts, but uses it in a different way. Once every 5 seconds,
  the ASOS computes the greatest 5-second average wind speed (and
  corresponding direction)  during  the past  minute,  and  once  each 
  minute stores this information in memory for 12 hours.</p>
  
  <p>Once every 5 seconds the ASOS computes the current 2-minute  average 
  wind  speed  and  compares  it  with  the greatest  5-second  average 
  wind  speed  during  the  past minute. If the current 2-minute average
  wind speed is equal to or greater than 9 knots and the greatest
  5-second average wind speed (during the past minute) exceeds the
  current 2-minute average speed by 5-knots or more, then the greatest
  5-second average speed observed during the past minute is stored in
  memory as a gust for 10 minutes.
  Once every 5 seconds, the ASOS compares the highest gust stored in memory 
  for the past 10 minutes with the current 2-minute average wind speed.
  If the difference between the two is 3 knots or more, the current
  reported wind speed is greater than 2 knots, and the highest gust
  exceeds the minimum 5-second wind speed in the past 10 minutes by 10
  knots or more, then the highest gust stored in memory is designated as
  the reportable gust. This value is appended to  the  current  wind 
  direction  and  speed  reported  in  the OMO,  computer-generated 
  voice  messages, and  the METAR/SPECI  reports. The minimum gust speed
  reported by ASOS is 14 knots. Wind speeds from 3 knots and 11 knots
  may be reported with gusts to 14 knots. For example, a 2-minute
  average wind of 240 degrees at 10 knots with gusts to 20 knots is
  reported as:</p>
  
  <p>“24010G20KT.</p>
</blockquote>

<p>Of course, the wind speed rules aren't standardized globally, as <a href="http://www.wral.com/weather/blogpost/1283652/" rel="nofollow noreferrer">this WRAL meteorologist discusses</a>.  In fact, they aren't even entirely consistent in the US, as the Hurricane Center <a href="http://www.aoml.noaa.gov/hrd/tcfaq/D4.html" rel="nofollow noreferrer">uses</a> a 1-minute average for sustained winds for hurricane intensity, and 3-5 second period for gusts.</p>

<p>So, even having done coursework on meteorological measurement systems, it's about as muddled to me now as it is to you. <strong>Probably report the most recent 2 minute average as the actual wind, and the highest instantaneous or 5-second average as the gust?</strong> (with requirement that it exceeds set criteria as <a href="https://earthscience.stackexchange.com/a/10443/6298">DavePhD's answer</a> alludes to, if you wish)</p>

CC BY-SA 3.0
2017-05-23T18:43:53.307Z
That's interesting. Especially since this definition is with a METAR context. However this seems to be far too complicated to implement for my basic use. My ultimate goal is it to give pilots in my area a hint on the weather. Gusts therefore are a very important element. Taking your last statement I will probably stick to the answer found on the website of the US weather service. However I probably will lower the bar when I count a temporary wind as gust. Still - I dislike that the METAR format didn't also specify how its values are computed...
binux
CC BY-SA 3.0
2017-05-23T22:07:01.963Z
@binux Agree with all you said :-)
JeopardyTempest
CC BY-SA 3.0
2017-05-23T07:09:00.607Z
2017-05-25T22:30:43.870Z
2017-05-25T22:30:43.870Z
JeopardyTempest
<p>A US <a href="https://graphical.weather.gov/definitions/defineWindGust.html" rel="nofollow noreferrer">definition</a> is:</p>

<blockquote>
  <p>Wind Gust: Is a sudden, brief increase in speed of the wind. According to U.S. weather observing practice, gusts are reported when the peak wind speed reaches at least 16 knots and the variation in wind speed between the peaks and lulls is at least 9 knots. The duration of a gust is usually less than 20 seconds. </p>
</blockquote>

<p>So it must be 9 knots above the non-gust background.  </p>

CC BY-SA 3.0
2017-05-23T18:34:37.633Z
I see where you got this. However do you think this can be also applied elswhere? I mean ins't there a worldwide standard?
binux
CC BY-SA 3.0
2017-05-23T18:47:24.197Z
@binux I can't answer that, but there is another US definition here http://www.ofcm.gov/publications/fmh/FMH1/FMH1.pdf saying 10 knots between peak and lull is required.
DavePhD
CC BY-SA 3.0
2017-05-24T22:36:13.063Z
Okay so since this is the easiest to implement I will accept your answer. It makes most sense to keep it simple. Based on @JeopardyTempest answer it will need some custom adjustments.
binux
CC BY-SA 3.0
2017-05-22T14:38:39.343Z
2017-05-22T14:38:39.343Z
DavePhD
<p>I'm currently building a weather station from scratch. It measures temperature, pressure, humidity, wind speed and direction. The end result shall be a weather station that sends out METAR weather messages so pilots can see live weather in our area.</p>

<p>Now I'm at the point where I'm writing the software and I have only little knowledge about meteorology. More specifically I ask myself when a meteorologist speaks about "gusts". I know it's a wind speed peak, but I'm a bit puzzled how much faster compared to the average wind speed a gust must be to be actually called gust?
I was searching for some definitions, but I didn't really find anything useful.</p>

<meteorology><wind>
What is the definition of wind gust?
binux
# What is the definition of wind gust?

(Asked by: username_0 on 2017-05-22)

I'm currently building a weather station from scratch. It measures temperature, pressure, humidity, wind speed and direction. The end result shall be a weather station that sends out METAR weather messages so pilots can see live weather in our area.

Now I'm at the point where I'm writing the software and I have only little knowledge about meteorology. More specifically I ask myself when a meteorologist speaks about "gusts". I know it's a wind speed peak, but I'm a bit puzzled how much faster compared to the average wind speed a gust must be to be actually called gust?
I was searching for some definitions, but I didn't really find anything useful.

**Tags:** meteorology, wind


---

## 2 answers

### Answer by username_2 on 2017-05-22. Score: 4 | Accepted answer

A US [definition](https://graphical.weather.gov/definitions/defineWindGust.html) is:

> Wind Gust: Is a sudden, brief increase in speed of the wind. According to U.S. weather observing practice, gusts are reported when the peak wind speed reaches at least 16 knots and the variation in wind speed between the peaks and lulls is at least 9 knots. The duration of a gust is usually less than 20 seconds.

So it must be 9 knots above the non-gust background.

> **Comments:**
> **username_0**: I see where you got this. However do you think this can be also applied elswhere? I mean ins't there a worldwide standard?  
> **username_2**: @username_0 I can't answer that, but there is another US definition here http://www.ofcm.gov/publications/fmh/FMH1/FMH1.pdf saying 10 knots between peak and lull is required.  
> **username_0**: Okay so since this is the easiest to implement I will accept your answer. It makes most sense to keep it simple. Based on @username_1 answer it will need some custom adjustments.  

---

### Answer by username_1 on 2017-05-23. Score: 4

Doesn't appear to be great sources out there for some of this info! (But then, that's what StackExchange has great promise in being!)

In the US, [this manual](http://www.nws.noaa.gov/asos/pdfs/aum-toc.pdf) for the official instrument setup, as well as this [old manual](http://www.nws.noaa.gov/om/forms/resources/SFCTraining.pdf) on how to take observations gives quite a bit of good detail on how wind observations are done...

In the US, **wind speed is the most recent 2 minute average**.

A thorough explanation for gusts for ASOS, which is about as readable as syrup:

> In the manual procedure, a gust is reported when an observer sees
> rapid fluctuations in sensor wind speed indications with a variation
> of 10 knots or more between peaks and lulls during the 10-minutes
> before the observation. The reported gust is taken from the maximum
> “instantaneous” wind speed observed during this period. The
> average 2-minute wind is used to report wind direction and
> wind speed. Conceivably, an average 2-minute wind speed as low
> as 3 knots (observed in the last minute) may be reported
> with a gust of 10 knots (observed in the last 10 minutes).
> Observations of 5 knots with gusts of 10 to 15 knots, however, are the
> more common minimum values reported.
>
> The ASOS algorithm also relies on a 10-minute observation period to
> determine gusts, but uses it in a different way. Once every 5 seconds,
> the ASOS computes the greatest 5-second average wind speed (and
> corresponding direction) during the past minute, and once each
> minute stores this information in memory for 12 hours.
>
> Once every 5 seconds the ASOS computes the current 2-minute average
> wind speed and compares it with the greatest 5-second average
> wind speed during the past minute. If the current 2-minute average
> wind speed is equal to or greater than 9 knots and the greatest
> 5-second average wind speed (during the past minute) exceeds the
> current 2-minute average speed by 5-knots or more, then the greatest
> 5-second average speed observed during the past minute is stored in
> memory as a gust for 10 minutes.
> Once every 5 seconds, the ASOS compares the highest gust stored in memory
> for the past 10 minutes with the current 2-minute average wind speed.
> If the difference between the two is 3 knots or more, the current
> reported wind speed is greater than 2 knots, and the highest gust
> exceeds the minimum 5-second wind speed in the past 10 minutes by 10
> knots or more, then the highest gust stored in memory is designated as
> the reportable gust. This value is appended to the current wind
> direction and speed reported in the OMO, computer-generated
> voice messages, and the METAR/SPECI reports. The minimum gust speed
> reported by ASOS is 14 knots. Wind speeds from 3 knots and 11 knots
> may be reported with gusts to 14 knots. For example, a 2-minute
> average wind of 240 degrees at 10 knots with gusts to 20 knots is
> reported as:
>
> “24010G20KT.

Of course, the wind speed rules aren't standardized globally, as [this WRAL meteorologist discusses](http://www.wral.com/weather/blogpost/1283652/). In fact, they aren't even entirely consistent in the US, as the Hurricane Center [uses](http://www.aoml.noaa.gov/hrd/tcfaq/D4.html) a 1-minute average for sustained winds for hurricane intensity, and 3-5 second period for gusts.

So, even having done coursework on meteorological measurement systems, it's about as muddled to me now as it is to you. **Probably report the most recent 2 minute average as the actual wind, and the highest instantaneous or 5-second average as the gust?** (with requirement that it exceeds set criteria as [username_2's answer](https://earthscience.stackexchange.com/a/10443/6298) alludes to, if you wish)

> **Comments:**
> **username_0**: That's interesting. Especially since this definition is with a METAR context. However this seems to be far too complicated to implement for my basic use. My ultimate goal is it to give pilots in my area a hint on the weather. Gusts therefore are a very important element. Taking your last statement I will probably stick to the answer found on the website of the US weather service. However I probably will lower the bar when I count a temporary wind as gust. Still - I dislike that the METAR format didn't also specify how its values are computed...  
> **username_1**: @username_0 Agree with all you said :-)  

---

