Transatlantic flights were among more than 115 grounded so far, with British Airways cancelling multiple domestic flights to Edinburgh, Glasgow and Manchester and services to European destinations.
"While this weekend's weather may result in minor delays and some airlines consolidating flights, significant disruption at Heathrow is not currently expected," said a Heathrow spokesman.
"We are working closely with our on-site Met Office to monitor the further snowfall expected throughout the weekend."
The new icy blast has been dubbed the "mini-Beast from the East", with disruption expected to be less widespread and sustained.
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