The level two alert, issued by the Met Office, means that there is a 60 per cent chance average temperatures will be 2C or below in Yorkshire over the next two days.
It also warns that there is a possibility of wintry showers, overnight frost and icy patches and people have been reminded to look out for vulnerable neighbours, family and friends during the alert.
Dr Mike Gent, deputy director for health protection, PHE Yorkshire and the Humber, said: “It’s very important to remember that cold does kill, even in places where the temperatures aren’t at their lowest. Most of our advice on keeping warm in cold weather may seem like common sense, but it’s important to remind people how cold can affect them.
“Our advice is that when indoors, have plenty of warm food and drinks to stay warm and try to maintain indoor temperatures to at least 18°C, particularly if you have to sit still for long periods, have long term illness or are 65 or over.
“Before bad weather arrives is a good time to think about how the bad weather may affect your friends and family, particularly if they are older or very young or have pre-existing health conditions. These groups can be particularly vulnerable to the ill-effects of cold so think now what you could do to help - if you, or they, are eligible for a flu vaccination make sure you get it as soon as you can.”