The Met Office has issued an urgent weather warning for Friday morning, with the yellow alert in place until 9am. The Met Office says areas of fog, dense in places, are likely to cause travel delays this morning.
As well as a danger on the roads, the forecasters say flights could be cancelled. Areas of fog, including some dense patches reducing visibility to less than 100 metres at times, will impact travel during the morning rush hour. Fog will, however, slowly lift and clear through this morning.
The Met Office says give yourself the best chance of avoiding delays by checking road conditions if driving, leaving extra journey time, or amending plans if necessary. Make sure you know how to switch on your fog lights, and check they are working before setting off on your journey.
Bus and train services, as well as flights and ferry travel may also be affected; check for updates from your travel company and follow their advice.
Be prepared for weather warnings to change: when a weather warning is issued, the Met Office recommends staying up to date with the weather forecast in your area.
The warning covers the whole of the south and east of the country, as far west as Bath and as far north as Birmingham, Peterborough and Norwich.