January is mild and damp in Rabat, the ocean keeping the capital far gentler than the cold inland cities. Daytime highs sit around 17°C — pleasant for walking the Kasbah des Oudayas and the riverside medina between showers — while evenings turn cool and a warm layer is welcome. It is the quietest month of the year here: the city government continues its unhurried rhythm, museums and the Hassan Tower esplanade are calm, and prices are at their lowest.
This is a month for the indoor and the sheltered. The Mohammed VI Museum of Modern and Contemporary Art, the Chellah necropolis under low winter light, and the blue-and-white lanes of the Oudayas all reward a slow visit. The Atlantic can be grey and blustery, so plan around the weather rather than against it — a wet morning often clears to a bright, sharp afternoon, and the long Bouregreg riverfront is bracing on a clear day.
January suits travellers who want an authentic, low-key Moroccan capital without crowds or heat. Rabat pairs naturally with Casablanca, an easy hour by train, and with Meknes and Volubilis inland. Beach plans aside, almost everything the city is known for stays open and uncrowded, and the mild maritime climate makes it a comfortable winter base by Moroccan standards.