In Karachi, the megalopolis at the mouth of the Indus, the average temperature ranges from 18.5 °C (65.5 °F) in January to 31 °C (88 °F) in June. Here, winter is pleasant and sunny (although it can sometimes be cold during the night). In the months preceding the monsoon, there can be scorchingly hot days, with peaks of 42/44 °C (108/111 °F), but it's more common for the temperature to remain about 35 °C (95 °F), though with a high humidity. Here are the average temperatures.
Although the rains in Karachi are not abundant, the sky in the monsoon period is often cloudy, especially in July and August; in winter, on the other hand, the sky is almost always clear.
The temperature of the Arabian Sea is warm enough for swimming all year round, while it becomes very warm in summer. Here are the average sea temperatures near Karachi.