METAR sky cover & cloud-type codes
Two code sets in a METAR:
| Section | Codes | Gives |
|---|---|---|
| Body | SKC/FEW/SCT/BKN/OVC |
Amount only |
Remarks (RMK) |
2- or 3-letter abbreviation + coverage in eighths (oktas) per layer | Cloud type and amount |
Body sky cover = layer amount in eighths (oktas) of the sky, summed from the surface up (TC AIM MET 8.1, Table 8.2):
| Code | Sky covered |
|---|---|
SKC |
No cloud |
FEW |
Less than 1/8 to 2/8 |
SCT |
3/8 to 4/8 |
BKN |
5/8 to less than 8/8 |
OVC |
8/8 |
CLR= AWOS equivalent ofSKC: no cloud detected below 25,000 ft.
Remarks cloud-type abbreviations (TC AIM MET 8.2):
| Abbr | Cloud type |
|---|---|
CI |
cirrus |
CS |
cirrostratus |
CC |
cirrocumulus |
AS |
altostratus |
AC |
altocumulus |
ACC |
altocumulus castellanus |
NS |
nimbostratus |
ST |
stratus |
SF |
stratus fractus |
SC |
stratocumulus |
CU |
cumulus |
CF |
cumulus fractus |
TCU |
towering cumulus |
CB |
cumulonimbus |
SF/CF: ragged ("fractus") forms.SF= broken-up stratus,CF= broken-up cumulus. Letter before F gives parent cloud.ACC: altocumulus with turrets (castellanus); plain =AC.- Example:
RMK SF5NS3= stratus fractus 5/8, nimbostratus 3/8.
Trap: CLR is automated-station only, not a human "sky clear" call. Humans report SKC. Also: confusing a remarks cloud-type code with a body sky-cover amount, or vice versa.
References
- TC AIM MET 8.1
- TC AIM MET 8.1 (Table 8.2, Sky Conditions for METARs)
- TC AIM MET 8.2