October to April is when Manama is worth visiting. Temperatures during these months range from the mid-teens at night in January to the low-30s in April — warm but manageable, and dry enough to walk around comfortably. November and March are the sweet spots: clear skies, low humidity, and no school holiday crowds. December and January bring a wave of visitors from elsewhere in the Gulf, particularly Saudi Arabia, so hotels fill up and prices rise.
June through September is genuinely brutal. Temperatures regularly exceed 40°C and humidity from the Gulf makes the heat feel worse than the thermometer suggests. Most outdoor activities become impractical between 10am and 5pm. If you're travelling in summer, plan around air-conditioned interiors and early-morning or late-evening movement.
Ramadan changes the rhythm of the city significantly. Daytime is quiet — restaurants close, the pace slows — but the evenings come alive in a way that is worth seeing if you have the chance. Iftar meals are elaborate, the souqs are busy late into the night, and there's a specific atmosphere that doesn't exist at any other time of year. Travelling during Ramadan requires adjustment but is not difficult.