The peak tourist season in Egypt runs from November through February, and prices for flights and hotels go up considerably during these months, by as much as 30%.  Most people avoid visiting Egypt from May through September, since the heat is unbearable, but it can often be quite pleasant in Alexandria at this time.

Alexandria has a cooler Meditteranean climate, unlike the rest of Egypt. Temperatures in summer are not as hot as Cairo, so many Cairo natives spend their summer vacation in Alexandria. But July and August can seem unbearably hot to many visitors.  If you plan to visit during that time expect significant crowds, and make your reservations well ahead of time. You will be guaranteed to see good weather, though, as summer temperatures usually reach around 85 degrees Fahrenheit. 

Also, you may want to avoid visiting during the month of Ramadan (which starts at a different time every year due to the lunar calendar), when Muslims fast from sunrise until sunset. Shops close early, many eateries are closed during the day, and eating and drinking in public during the day is not normal (but it is not illegal like in some other Muslim countries). Everything is still open at night, however, and the locals often celebrate into the wee hours.

It should be noted though, that the weather in Alexandria during the months of November to February can sometimes be quite unpleasant for visitors. Thunder storms, heavy wind and rain and sometimes a very cold wind are usual at this time of year. Bad weather normally runs in cycles of about 3 days very bad weather and a week or so of good weather. If you are travelling through Egypt at this time and expect to visit Alexandria you should bring a coat and warm footwear.

The best time of year to visit Alexandria is probably autumn or fall (late September to early November) and spring (March and April). It is possible to swim in the sea or a pool without getting too hot.