When and why do we issue warnings

One of the most common ways you might know us is through our National Severe Weather Warning Service, or more colloquially, our ‘weather warnings’.  

However, how do you know what you should do when you’re in a warning area?  

• Why do we issue warnings? 

• When do we warn for the weather? 

• What should you do when there’s a warning? 

• What steps can you take to prepare and minimise impacts?  

Why do we issue warnings?  

Warnings are designed to let people, businesses, emergency responders and governments know what weather is in store and what the impacts of that weather could be.  

In its simplest form, issuing weather warnings is an effective way to tell a large group of people about impactful weather in the forecast.  

When do we warn for the weather? 

From 2011, we moved to impact-based warnings, which means that weather is warned for when it is deemed to have potential impacts on people.  

This was a change from previous years when warnings were issued when certain weather thresholds, or levels, were reached. 

The guidance on warnings that our expert meteorologists work from today includes awareness of the wider context of the weather occurring. This means they consider other factors that could make the weather particularly impactful. These factors include:  

• What time of day is it? Could it affect rush hour traffic? 

• What time of year is it? Is the weather unseasonable? 

• How unusual is the weather? Is the region affected ‘used to’ this weather? 

• Are there any outdoor events or activities in the area? 

• Are there any ongoing sensitivities to weather within the area? 

In practice this means that while strong gusts of wind over a field in the middle of winter might not warrant a warning as there’s not much tangible impact, that same level of gust in the summer with people camping outside could see a warning issued.

In addition, this means that while light snow on the tops of mountains in the north of the UK would be unlikely to create significant impacts so wouldn’t warrant a warning, that same level of snow in a city further south, where this weather is less common, might get a warning.  

What should you do when there’s a warning? 

Weather warnings are designed to let people know there’s a potential for impacts in their location. This means that any warning we issue should make you think about what steps you can take to minimise the chances of disruption for you.  

• Yellow: You should check the details of the forecast and consider taking steps to minimise impacts for you and your household.  Even in a yellow warning area, people will see disruption to a greater or lesser extent, so it's important to check the details and see which steps you could take to prepare. 

• Amber: Disruption from an Amber warning is more likely and more widespread. You should change plans that could be impacted by the weather and take action to protect yourself and your property.  

• Red: These warnings are reserved for very dangerous weather with a high level of certainty. You should take direct action to keep yourself and others safe from impacts of the weather. It’s likely there will be a risk to life, as well as substantial disruption to travel and infrastructure. 

What actions can you take to minimise the chance of impacts from the weather? 

Our WeatherReady advice provides a wealth of information from our partners with simple actions anyone can take to minimise the impacts of severe weather. 

For an in-depth look at weather warnings, the impacts matrix and how the service is used, visit our Weather Warnings Guide. For the types of weather we warn for, visit our Impact Tables Guide.  

Find out more advice to help you get around and make the most of the weather throughout the year.