Frosty mornings and freezing overnight temperatures have been forecast for Essex until Wednesday morning.
Met Office forecasters say conditions will plummet to as low as -4C in the east of England. It has issued a yellow warning for ice in the region as a result.
Daytime temperatures for the rest of today and Tuesday are unlikely to go any higher than 4C.
Fortunately, milder weather is forecast for the start of 2015.
A Met Office spokesman added: "Prolonged periods of cold weather can be dangerous, especially for the very young, very old or those with chronic diseases."
It will start to warm up on New Year's Eve, though rain is also forecast. Temperatures will rise to as high as 8C on Thursday before creeping as high as 12C.
