Weather forecasts from the Met Office are provided at a range of time-scales and for up to 5000 locations across the UK. Seven-day forecasts extend into the medium-range forecasting period. The different forecasting periods that seven-day forecasts cover are described below.
Nowcasting maps the current weather and then uses an estimate of its speed and direction of movement to forecast the weather a short period ahead - assuming the weather will move without significant changes.
At the Met Office, nowcasting is combined with the latest high resolution model output to form a detailed forecast out to six hours. This forecast is updated every hour.
Short range weather forecasts cover periods from just a few hours ahead (from the nowcasting time-scale) up to about three days ahead.
Short-range forecasts provided by the Met Office are extremely accurate and are updated several times a day.
Medium-range weather forecasts cover anything from around three to 10 days ahead.
Seven-day weather forecasts extend into the middle part of the medium-range forecast period.
The UK medium-range outlook is covered in the 5-day location and map-based forecasts as well as the forecaster written forecasts.
The regional 3-5 day text forecasts provide a general picture of the weather on a day-by-day basis, with the main regional variations identified. The Met Office has a good track record in advising on any significant risk of severe weather in this period.
The 6-15 day text forecasts provide a broad description of the weather likely to be affecting the UK, including significant changes in the type of weather. It also provides a risk assessment of severe weather, such as heavy rainfall, severe gales or an extended period of high or low temperatures.
When looking at forecasts up to seven-days in the future the chaotic nature of the atmosphere begins to play a larger part - small events currently over the Atlantic can have potentially significant impacts on our weather in the UK in several days time. Therefore whilst we can still forecast the general feel of the weather to a relatively high level of accuracy using our ensemble models, it becomes harder to offer local detail to as high a level of accuracy as our shorter range forecasts. For this reason our forecasts for 5 days and beyond are written on the scale of the UK as a whole.