Cairo's weather is a major factor in determining when to visit. There is almost no rain to speak of, so precipitation is not an issue. The biggest issue is in fact the heat. Cairo basically has two seasons that can be categorized as winter and summer, with a windy season that occurs in late winter.

Winter

Cairo's winter essentially lasts from November through April. December through February are not surprisingly the most popular tourist months in Cairo, as temperatures are at their coolest. Be prepared for the cold nights however, when temperatures can dip to as low as 8 degrees C. You'll definitely want a jacket for the nights, and probably a wrap or jacket for daytime as well. A wrap is generally necessary anyway, as in Egypt dress is very modest.

Winds

Bear in mind that come March and April there are gale force winds that can hit Cairo with little warning. Windstorms can last several days and keep people indoors. They also cause temperatures to fluctuate drastically with sudden rises during the storms and dips afterward. Dust clouds will descend upon the area, so if you are going to brave the outdoors it may be wise to bring something to protect your face.

Summer

From May through October the summer heat can become unbearable, reaching 40 degrees C at midday. It is also more humid in the summer. Keep in mind that deserts do not retain heat, however, and bring a wrap with you for the cooler nights. Another thing to consider about summer travel if the heat doesn't bother you is that schools holidays make the streets more crowded and noisy. Pollution levels are usually at their highest in late summer.

There are a few other factors to keep in mind when planning your trip to Cairo. In the summertime prices can be driven up by the amount of tourists from neighboring countries who are escaping their own countries' oppressive heat for the slightly milder Egyptian summers. Prices also tend to peak at Christmas and Easter, when many tourists book their holidays. Also, during Ramadan it can be difficult to do things during the day, though the nightlife is definitely more colorful. One last thing worth noting is that if you're going to be taking any day trips into the desert, especially in the winter, you should bring heavy layers and a winter jacket.