A basic lesson in METAR 

METAR is a standardized way of communicating meteorological information in aviation. You probably won't ever need to use it, but I figured I'd give you a short lesson anyways using this METAR string:
KGKY 191853Z 17019G29KT 10SM SCT022 SCT033 26/19 A2990 RMK AO2 PK WND 14032/1843 SLP118 T02610194

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A basic lesson in METAR 

The first two are basic information. KGKY is the airport (in this case, Arlington Regional) and 191853Z is the date and time it was issued. The first two digits are the day of the month (19 for, well, the 19th), the last four plus Z is the time *in UTC*. So, 18:53 UTC, KGKY is in CDT (UTC-5:00), so it was issued at 13:53 CDT.

A basic lesson in METAR 

The next chunk is wind information. The first three digits give the wind direction in degrees from north. So, 170 would be 170° off north or just off south (southeast by south). The rest is the speed in knots (hence the KT at the end). In this case, we have a wind gust. The digits before the G are the normal wind speeds (19 knots), the digits after are gust speeds (gusting up to 29 knots).

A basic lesson in METAR 

Next, we get visibility and cloud coverage. Visibility is given in statute miles (the SM), so, right now, visibility is 10+ statute miles. (Note that it only ever reads up to 10. So, 10 is implied 10 or more.) Then we get cloud coverage. Here, there are two cloud layers. The letters indicate how much of the sky is covered, the numbers at what altitude (in *hundreds* of feet). So, we have scattered clouds at 2200 and 3300 feet.

A basic lesson in METAR 

The cloud coverage is given by a phrase that represents some number of eighths of the sky covered. SCT (scattered) is 3-4 oktas (1/8ths of the sky). Other phrases:
CLR (clear): no clouds
FEW (few clouds): 1-2 oktas
BKN (broken): 5-7 oktas
OVC (overcast): 8 oktas

CLR could also be replaced with SKC (sky clear), NCD (no clouds detected), or NSC (no significant clouds) depending on where you are and how the report was generated.

A basic lesson in METAR 

After cloud coverage is the temperature and dew point in degrees Celsius. So, right now, it's 26°C with a dew point of 19°C. If the temperature is below zero, it will be prefixed with M. So, 09/M03 would be 9°C with a dew point of -3°C.

A basic lesson in METAR 

Finally in the main portion is the altimeter setting, which is just barometric pressure, given in inHg. The decimal is omited, but it's always given as four digits, two before and two after. So, right now, the pressure is 29.90 inHg, or about 759 mmHg.

A basic lesson in METAR 

RMK denotes the start of the remarks section. I'm not going to go too in-depth here, but I'll cover some basics of what we've got. AO2 denotes that this was done by an automated station with precipitation discriminator. PK WND is peak winds. SLP is sea level pressure (in kPa, iirc, so 118 kPA or ~34 inHg). And T is the temperature to the tenths place in °C (26.1°C, dew point of 19.4°C. If it's below zero, the 0 at the front becomes a one (M09 -> 109X).

A basic lesson in METAR 

So, there you go. Now you're capable of reading METAR! Now, why not go try it yourself? You can find METAR data for any US airport at aviationweather.gov/metar. Why not try finding an airport near you (assuming you're in the US) and seeing what it's reporting the weather as?

A basic lesson in METAR 

Oh. Correction: It seems that the NOAA aviation weather site *does* have METAR data for other countries. So, yeah. Why not give it a shot?

A basic lesson in METAR 

And a small addendum: Most countries, instead of AXXXX, have QXXXX, where the pressure is given in hPa instead of inHg. So, in the string I used, A2990 could be replaced with Q1012 and would be outside of the US.

A basic lesson in METAR 

Similarly, visibility will just be given as a number in meters, rather than as some number of statute miles. So, for our example, 10SM might be replaced with 9999 to indicate 10+ km visibility

A basic lesson in METAR 

ofc, there's always more to learn. For instance, you might have TSVC (thunderstorms in the vicinity) or +RA (heavy rain) or FZFG (freezing fog). If you're interested and want to know more, I'd encourage checking the Wikipedia article, as it goes into various other bits you can have in METAR strings, including WX codes like the ones I just gave and various bits that might come after RMK in the US.

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