An “extreme weather” alert has been issued for London tonight with warnings of heavy snowfall and temperatures as low as -6°C in the suburbs.

The Met Office said exceptionally heavy snowfall was expected from about 8pm, with the potential for up to 25cm to fall in some parts of the capital. Widespread disruption is expected on London's transport network tomorrow, with commuters being urged to check their route before leaving home.

The BBC weather centre forecast "heavy snow" tonight and tomorrow in Hounslow, with temperatures dropping as low as -4°C. In Richmond, light snow showers were forecast, with temperatures as low as -6°C.

Council gritters are expected to be out in force tonight in Richmond. In Hounslow, a council spokeswoman said gritters would be out from 7pm and were likely to back out early tomorrow.

This afternoon some London schools alerted parents that they may not be able to open tomorrow. Many will take the decision first thing tomorrow.

The Met Office said: “There is a high risk of an extreme weather event, a period of exceptionally heavy snowfall, affecting parts of southern England.”

Hounslow Council said 150 tonnes of grit had been used in the area so far this winter. The authority has 800 tonnes left in stock and officials are monitoring weather reports, a spokeswoman added.

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