The dry, dust-laden wind that blows south from the Sahara across West Africa, roughly December to February.
The sky goes hazy, visibility drops, and a fine layer of dust settles on everything you own. Nights are noticeably cooler, which after months of humidity is a genuine pleasure.
Practically: skin and lips crack, eyes dry out, asthma and allergies get worse, fire risk rises, and flights are occasionally disrupted by poor visibility.
Moisturiser, lip balm, eye drops, and an inhaler kept topped up if you use one.