| Legend |
| None |
No visibilities below 1/4 mile. |
| Slight |
Patchy (1-20% coverage) visibilities < 1/4 mile in fog
or < 1 mile in heavy rain |
| Moderate |
Areas (30-50% coverage) of visibility < 1/4 mile. |
| High |
Widespread (60-80% coverage) visibilities < 1/4 mile. |
| Extreme |
Total (>80% coverage) visibilities < 1/4 mile. |