| Decade | Description |
| 00-03 | Cloud characteristic changes |
| 04-09 | Smoke, haze, or airborne dust |
| 10-12 | Mist or shallow fog |
| 13-19 | Thunderstorm (no rain), squall, or distant precip |
| 20-29 | Precipitation or fog during past hour, none now |
| 40-49 | Fog or ice fog at observation time |
| 50-59 | Drizzle |
| 60-69 | Rain (continuous or intermittent) |
| 80-99 | Showers or thunderstorm at station |