• home

Frequently asked questions — NSWWS improvements

What is National Severe Weather Warning Service?

The National Severe Weather Warning Service (NSWWS) is produced by the Met Office as a part of our commitment to the Public Weather Service (as defined in the Civil Contingencies Act 2004). The warnings are required for two purposes:

  1. To enable civil emergency authorities and the Ministry of Defence to trigger plans to protect the public from impacts, in advance of an event, and help them recover from any impacts after the event.
  2. To alert the public to take action prior to the event.

Why are you making these changes?

The changes are being made following consultation over the past 12 to 18 months with the public and those with responsibility for protecting the public. In addition they address customer feedback from the public. The improvements reflect the latest requirements of warnings users.

What are the changes?

The key changes are:

Improved website display
We will be changing the way warnings are displayed on our website to make it easier to find the information that is relevant to your area. You will then be able to see at a glance the information you are interested in and, if you wish, drill down to find more detail.

Easier to understand
We will be making the warnings easier to understand by:

  • simplifying the language to make it less technical;
  • replacing the current Early, Flash and Advisory categories with Alerts (issued more than 24 hours ahead) and Warnings (issued up to 24 hours ahead).

More impact–based
Warnings will now be based on both the expected weather conditions and the potential impact they may have, recognising that the same weather in different parts of the UK can have a different impact.

Consistent language
We have made the language used in warnings consistent with that used by others, including the Environment Agency in relation to flood warnings.

What are the benefits of the changes?

The changes to the warnings service will help to bring the following benefits to users:

  • Easier to understand warnings.
  • Basic information at a glance.
  • Fewer but more relevant warnings.

What do the colours mean?

The combination of likelihood and impact will be measured against a matrix to give each warning a colour:

  • red;
  • amber;
  • yellow.
You can follow this simple guidance for each colour:

Green implies no severe weather, yellow implies be aware, orange implies be prepared, red implies take action

Find out more about the warnings colours.

What do the warnings icons mean?

Warnings are issued for

  • Rain
  • Wind
  • Fog
  • Snow
  • Ice

Each warning type has been given a corresponding symbol so that it is easy to identify visually. Symbols are also helpful for overcoming language barriers. A key to the symbols can be found below:


rain Rain wind Wind ice Ice
snow Snow fog Fog

What should I do if a warning is issued?

For information on what to do before, during and after severe weather please visit our severe weather advice pages.

What is the difference between an alert and a warning?

The only difference between Alerts and Warnings is lead time on which they are issued. Alerts are issued more than 24 hours ahead, while Warnings are issued up to 24 hours ahead.

How will I know if severe weather is expected?

Weather warnings will be displayed on all our distribution platforms including our website, iPhone, mobile, Weather Widgets, Desktop Widget and email alerts. Some of these will simply carry a summary of warnings that have been issued and refer you back to our main website for more details, but all will alert you that warnings are in force.

Where can I find more details about the warnings changes?

You can find out more about the changes on our guide page, or alternatively a video walkthrough is provided.

If two areas are both expecting the same weather conditions why does only one have warnings in force?

An example of this may be when 70 mph winds are expected across the whole of the UK, yet warnings may be in force for south-east England but not for Scotland. This is because warnings are no longer purely based on meteorological criteria but instead take into account the possible impacts these may have. In this example 70 mph winds would be unlikely to cause many issues for Scotland but could cause disruption in south-east England, so warnings would be in force for the latter.



Get updates