Home / Editor's Pick /

British Science Week: How are weather forecasts created?

09:00
16 March 2023

British Science Week
How are weather forecasts created?

Rainy window with sun drawnWhether it's rain or sun, accurate weather forecasts are important in planning our day-to-day activates.

There is no better time to look deeper into meteorology than on British Science Week so today were letting you into the world of forecasts.

Meteorologists use some of the world’s most powerful super-computers to produce our weather forecasts.

These incorporate a vast amount of data and perform trillions of calculations per second to give us an idea of how the weather will change in the coming days.

Due to the complexity of the atmosphere however, even these weather forecasts tend to only be reliable for up to five days or so.

If the weather conditions are particularly complex, there can still be a degree of error even within the five-day period.

Any forecast that offers an outlook greater than ten days’ time is not considered a forecast but a trend.

To produce these forecasts, meteorologists usually run their forecast models a number of times and group the forecasts into what are known as clusters.

This gives probabilities of what may happen in the future, rather than one single solution.

Short-term forecasts cover a period of 24 hours up to three days. We see these on the TV every day. They are generated using synoptic meteorology – current atmospheric observations – and numerical models.

Medium-range forecasts cover between three and 10 days with long-term forecasts covering periods over 10 days away. Both are generated by using weather ensemble models to create a weather trend.

For both ranges, conditions tend to be described as wetter or drier, warmer or cooler with no specific information.

You can find all of this work in action each and every day with your local forecast in the app, and see it visualised via the WeatherRadar.

Ryan Hathaway
More on the topic
Split weather map comparing two wind conditions over the Atlantic. The left side shows a powerful cyclone near the US East Coast, with a distinct eye surrounded by intense purple and red bands of strong winds. The right side shows calmer conditions, mostly green shading with lighter winds illustrated by white streamlines and small yellow patches. An arrow in the centre indicates the transition from storm to calmer weather.
Wednesday 10 September 2025

Since Erin

Hurricane season exceptionally calm
Curvature of the Earth with cloud fields and deep blue sky from a great height.
Tuesday 16 September 2025

Protective layer recovers

Ozone hole significantly smaller in 2024
The map shows the strength of the wind over the Atlantic. A tropical storm over the open sea, not yet threatening any land.
Thursday 18 September 2025

Quiet hurricane season

Atlantic: Tropical Storm Gabrielle on its way
All weather news
This might also interest you
Sunday 24 August 2025

Your weather - Your shots

Mammatus clouds widely spotted
Monday 25 August 2025

Bank holiday outlook

Warm day turning gusty in places
Weather map of the UK and Ireland showing scattered showers with cloudy patches across much of the region, especially around western and northern areas. Sunshine symbols appear over London, Cardiff, and parts of southern England, while temperatures range from 17°C to 18°C in most places. Areas of heavier rain are visible over the Atlantic to the west.
Friday 29 August 2025

Breakfast brief

Unsettled conditions into the weekend
All articles
Weather & Radar

www.weatherandradar.ie

facebooktwitteryouTubeContact uslinkList
Privacy Policy | Legal info | Accessibility statement