Any or all of the forms of water particles, whether liquid (e.g. rain, drizzle) or solid (e.g. hail, snow), that fall from a cloud or group of clouds and reach the ground. (See Drizzle, Rain).

Duration of precipitation

• Brief: Short duration.
• Intermittent: Precipitation which ceases at times.
• Occasional: Precipitation which while not frequent, is recurrent.
• Frequent: Showers occurring regularly and often.
• Continuous: Precipitation which does not cease, or ceases only briefly.
• Periods of rain: Rain is expected to fall most of the time, but there will be breaks.

Intensity of precipitation

• Slight or light:
  
  • Rain: Individual drops easily identified, puddles form slowly, small streams may flow in gutters.
  • Drizzle: Can be felt on the face but is not visible. Produces little runoff from roads or roofs. Generally visibility is reduced, but not less than 1000 m.
  • Snow: Small sparse flakes. Generally visibility is reduced, but not less than 1000 m.
  • Hail: Sparse hailstones of small size, often mixed with rain.
• Moderate:
  
  • Rain: Rapidly forming puddles, down pipes flowing freely, some spray visible over hard surface.
  • Drizzle: Window and road surfaces streaming with moisture. Visibility generally between 400 and 1000 m.
  • Snow: Large numerous flakes and visiblity generally between 400-1000 m.
  • Hail: particles numerous enough to whiten the ground.
• Heavy:
  
  • Rain: falls in sheets, misty spray over hard surfaces, may cause roaring noise on roof.
  • Drizzle: Visibility reduced to less than 400 m.
  • Snow: Numerous flakes of all sizes. Visiblity generally reduced below 400 m.
  • Hail: A proportion of the hailstones exceed 6 mm diameter.

Distribution of showers and precipitation

• Few: Indicating timing not an area.
• Isolated: Showers which are well separated in space during a given period.
• Local: Restricted to relatively small areas.
• Patchy: Occurring irregularly over an area.
• Scattered: Irregularly distributed over an area. Showers which while not widespread, can occur anywhere in an area. Implies a slightly greater incidence than isolated.
• Sporadic: scattered or dispersed in respect of locality or local distribution. Charaterised by occasional or isolated occurrence.
• Widespread: Occurring extensively throughout an area.