January–March: cool, occasional rain
January is the coolest month: Tunis 7–15°C, occasional rain (60 mm), sea at 15°C. February similar but slightly drier. By March temperatures begin to climb (10–20°C on the coast) and the southern desert reaches a comfortable 22°C by day. Pack layers, a light rain jacket, warm clothes for desert nights.
April–June: warming, dry, ideal
April brings 14–23°C on the coast and 18–28°C in the desert with almost no rain. May warms to 17–27°C; by late May the sea hits 20°C. June is the first proper beach month: 21–29°C on the coast, 25–35°C inland, sea at 22°C. Pack a sweater for early-morning desert excursions.
July–August: hot, peak season
July: coast 23–32°C, inland 25–38°C, sea at 25°C, zero rain. August: coast 24–33°C, inland 26–42°C (Tozeur regularly 40°C+), sea at 26–27°C. Cap Bon and Tabarka benefit from a coastal breeze; the south becomes difficult. Pack only summer clothes and high SPF.
September–October: the perfect window
September is statistically the best month: coast 22–31°C, inland 22–35°C, sea peaking at 26°C, almost no rain. October cools to 18–27°C on the coast, 17–28°C inland, sea still at 23°C. Late October sees the first autumn rain in the north. Pack a light jacket for evenings.
November–December: cool and quiet
November averages 14–22°C with light rain (40 mm). December is the wettest month in the north (80 mm), with 10–18°C on the coast and 7–17°C in the desert. The south stays mostly dry. Pack a warm layer and a rain jacket — coats are needed only at altitude.