You can plan your beach trip with a look at year-round temperatures in Siwa: The hottest months are usually July and August, with an average temperature of 30°C, while the coldest months are January and February, with an average of 15°C. Between January and March, the daytime average is 24°C and the night-time average is 9°C. Between April and June, temperatures average 37°C during the day and 16°C at night. Between July and September, the temperature averages 38°C during the day and 22°C at night. Between October and December, the average temperature is 30°C during the day and 10°C at night.