What does this forecast mean?
Forecast table explained:
Weather symbols
|
Clear night |
Sunny day |
Partly cloudy (night) |
|
Sunny intervals |
Mist |
Fog |
|
Cloudy |
Overcast |
Light rain shower (night) |
|
Light rain shower (day) |
Drizzle |
Light rain |
|
Heavy rain shower (night) |
Heavy rain shower (day) |
Heavy rain |
|
Sleet shower (night) |
Sleet shower (day) |
Sleet |
|
Hail shower (night) |
Hail shower (day) |
Hail |
|
Light snow shower (night) |
Light snow shower (day) |
Light snow |
|
Heavy snow shower (night) |
Heavy snow shower (day) |
Heavy snow |
|
Thunder shower (night) |
Thunder shower (day) |
Thunder |
Chance of precipitation
For example, a 70% chance of rain represents a 7 in 10 chance that precipitation will fall at some point during that period.
Represents how likely it is that rain (or other precipitation: sleet, snow, hail, drizzle etc.) will fall from the sky during a certain time period.
Temperature
The number in the coloured bars represents the air temperature in the units selected in Settings (Celsius or Fahrenheit)
Feels like
Feels like temperature takes into account wind speed and humidity to give a more representative indication of how the temperature will feel.
Wind direction and speed
The speed represents the average wind speed during the time period, i.e. the mean wind speed you may encounter (in reality the wind will strengthen and lull constantly above and below this value).
The arrow shows the direction that the wind is blowing, and the letter represents the direction the wind is blowing from (on a standard 16-point compass rose).
For example, an arrow pointing upwards indicates a wind blowing from the south to the north, along with the letter S to indicate that it is a southerly wind.
NNW would indicate a wind blowing from the north northwest.
Wind gust
This value represents the highest wind speed that you should encounter during the time period, as the winds peak, and then lull again.
Strong winds are shown in bold and represent speeds of 25 knots (or 29 miles per hour) or above.
UV
|
UV |
UV SUMMARY |
EXPOSURE CATEGORY |
|---|---|---|
 |
No significant UV | |
  |
 |
Low |
   |
 |
Moderate |
  |
 |
High |
   |
 |
Very high |
 |
 |
Extreme |
 |
|
No data |
Air pollution
| Symbol | Category |
|---|---|
 |
No significant pollution |
 |
Low |
 |
Moderate |
 |
High |
 |
Very high |
|
No data |
Pollen
| Symbol | Category |
|---|---|
 |
No significant pollen |
 |
Low |
 |
Moderate |
 |
High |
 |
Very high |
|
No data |
Pressure symbols
 |
Cold FrontThe leading edge of an advancing colder air mass. Its passage is usually marked by cloud and precipitation, followed by a drop in temperature and/or humidity. |
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Warm FrontThe leading edge of an advancing warmer air mass, the passage of which commonly brings cloud and precipitation followed by increasing temperature and/or humidity. |
 |
Occluded front (or 'occlusion')Occlusions form when the cold front of a depression catches up with the warm front, lifting the warm air between the fronts into a narrow wedge above the surface. Occluded fronts bring cloud and precipitation. |
|
|
Developing cold/warm front (frontogenesis)Represents a front that is forming due to increase in temperature gradient at the surface. |
|
|
Weakening cold/warm front (frontolysis)Represents a front that is losing its identity, usually due to rising pressure. Cloud and precipitation becomes increasingly fragmented. |
|
|
Upper cold/warm frontUpper fronts represent the boundaries between air masses at levels above the surface. For instance, the passage of an upper warm front may bring warmer air at an altitude of 10,000 ft, without bringing a change of air mass at the surface. |
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Quasi-stationary frontA stationary or slow-moving boundary between two air masses. Cloud and precipitation are usually associated. |
 |
IsobarsContours of equal mean sea-level pressure (MSLP), measured in hectopascals (hPa). MSLP maxima (anticyclones) and minima (depressions) are marked by the letters H (High) and L (Low) on weather charts. |
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Thickness linesPressure decreases with altitude, and thickness measures the difference in height between two standard pressure levels in the atmosphere. It is proportional to the mean temperature of this layer of air, so is a useful way of describing the temperature of an airmass. Weather charts commonly show contour lines of 1,000-500 hPa thickness, which represent the depth (in decametres, where 1 dam = 10 m) of the layer between the 1,000 hPa and 500 hPa pressure levels. Cold, polar air has low thickness, and values of 528 dam or less frequently bring snow to the UK. Conversely, warm, tropical air has high thickness, and values in excess of 564 dam across the UK often indicate a heatwave. |
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TroughAn elongated area of relatively low surface pressure. The troughs marked on weather charts may also represent an area of low thickness (thickness trough), or a perturbation in the upper troposphere (upper trough). All are associated with increasing cloud and risk of precipitation. |
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Convergence lineA slow-moving trough, which is often parallel to the isobars and tends to be persistent over many hours. They are quite common in cold northerly outbreaks down the Irish Sea, affecting west Wales, Devon and Cornwall in particular, but can be found in other areas also. This convergence line can give hours of persistent precipitation over very localised areas, whilst a few miles down the road it is relatively dry, leading to some heavy snowfall/rainfall. In summer the convergence lines are not as easy to forecast, but then can still occur due to sea-breeze convergence, and are over the land, whilst in winter they are over the sea. |
