Nigeria is known to be a hot country during most time of the year since its found in the tropics except towards the end of the year when it tends to become colder.
Most parts of Nigeria experience the harmattan and during this period, it is often times colder and drier than the usual weather and it is very vital you protect yourself from the cold.
Some Nigerians love the harmattan season and can even decide to sleep naked because it's not an extreme form of cold but for some others, they do feel cold and will need to wear clothes that will protect them from the harmattan cold and dryness.
You should wear clothes that will insulate your body from cold as well as the one that will attract and keep heat to your body rather than one that makes you lose heat. An example of such clothing is a cotton-like fabric made of wool.
Wearing wool based clothes, a sweater, wearing double or triple layered clothes, having warm water baths, early morning exercise and so on. You should also use a good body cream that is moisturizing as well as being able to protect your skin from the harsh harmattan weather.
This season does not last for long in Nigeria, it may only last for 2 months so stay warm by dressing smarter.