The cold weather affects seniors more mostly due to the reason of poor circulation making it harder for older people to stay warm in cooler conditions.
As you get older then your blood flow and circulation is not as good as it was when you were younger and as a result you feel colder and can't tolerate the colder temperatures as much as you could when younger.
Some older people like their homes more warm in the winter than other people do.
Colder conditions can make the pain of arthritis worse and cause elderly more heart problems especially if they do exhausting work such as shoveling snow.
There's also the risk of falling on ice or other slippery parts of their home during cold winter conditions and not being able to get up or summon help.