A very rough and ready guide to decoding the weather and cloud information in the metar reports

On the right of the AWS reports, information on visibility, weather and cloud is given for a handful of manned weather stations (mostly major airports), as well as for a few high-tech automatic weather stations. Here's how to decode them. Take this example:

|VIS WEATHER CLOUD --- --------- --------- ---------
| *= Level 1 Level 2 Level 3 Level 4
| auto

| 2.5 0.6. 2, 1.7. 120 3.7. 300 3.9. 1050

Visibility is 2.5km. No asterisk, so it was estimated by a human

Weather is 0.6.2. Check the 3 weather codes below, and you'll see the 0=light, 6=showers (of) and 2=rain.

Three layers of cloud are reported:
1.7.120 = 1 octa (eighth) of cloud cover (7=stratus, see code below) at 120metres
3.7.300 = 3 octas stratus at 300m
3.9.1050 = 3 octas cumulonimbus at 1,050m

The 3 weather codes

First figure: WxInt Weather intensity/Proximity
1=Moderate or Not Applicable
3=In the vicinity

Second figure: WxDesc Weather description
1=Shallow (of Fog etc)
2=Broken or in Patches (of Fog etc)
3=Partial (over part of Airport) (of Fog etc)
4=Drifting (of Snow Dust etc)
5=Blowing (of Snow Dust etc)
6=Showers (of Precipitation)
7=Thunderstorm (with or without Precipitation)
8=Freesing (of Fog, Mist, Precipitation)

Third figure: WxWx1 Weather phenomena
4=Snow Grains
5=Ice Crystals
6=Ice Pellets
8=Soft hail
12=Volcanic Ash
16=Dust Devils
18=Funnel Cloud

There can be up to three weather phenomena codes separated by commas (WxWx1, WxWx2, WxWx3), so 2.6.3,6,8 = heavy showers of rain mixed with ice pellets and soft hail is possible. However, either because we don't often have such exotic weather or because the coding gets complicated, the second and third weather codes are not often seen.

Cloud codes

0 Cirrus
1 Cirrocumulus
2 Cirrostratus
3 Altocumulus
4 Altostratus
5 Nimbostratus
6 Stratocumulus
7 Stratus
8 Cumulus
9 Cumulonimbus
32 Towering Cumulus