To Speak about weather, it is important to realize that in Egypt weather is different from one place to another/

The high season for tourism in Egypt is all year with winter and spring being peak season for cultural travels with lots of sightseeing.  Weather in Egypt is perfect for many kinds of tourism, and if coming in June, July and August , head for the seaside resorts. Those months are hot with temperatures that can reach around 45 degrees C. and the humidity is about 70 to 80%, but it is bearable with the sea and large swimming pools nearby.

So the period of high summer season is also crowded as hotels fill up with tourists from all over the world looking for a bargain, lots of sunshine, diving, snorkelling etc. It is also a primary vacation time in Europe. If you come in the deep summer season you can still enjoy it because you can always sightsee early in the morning and go again at night when the sun sets. You will definitely need good sunscreen and lot of liquids to drink with a nice hat on your head.

It is not true at all that Egypt  has only 2 seasons with 9 months of summer and the remainder winter.  There are 4 distinguishable seasons.

The best times to visit Egypt are from September till March, during which time the weather is good; and from September till mid-November, when it is very nice and the temperatures are pleasant for all activities - around 25 C to 15 C. Mid-Nov till the end of February is winter time when temperatures during day are around 12 or 15 degree C, and at night can drop to about 7 or 8 C.

From March until the end of April, there is usually some sand blown about by high winds.  However on some days--perhaps only two or three during this two-month period, the weather can be so dusty that you may be not able to go outside.  But the majority of days there is just a small amount of dust in the air because of wind that blows through the desert from the west.

Egypt is perfect all year for snorkelling, diving, and so on, in the Red Sea area in Hurgada and Sharm el Sheikh. In winter time it gets both windy and chilly there, which makes it perfect for windsurfing and kiting.  

So in speaking about when to visit, it's all up to you. If cost doesn't matter, then winter is when you will want to go, especially Christmas and New Year or the period of Easter from mid-March till end of April.  That is when the best weather will occur, even though it gets chilly in December and January but it's still suitable for many aspects of tourism during that time.

From mid-March till end of April, is the Easter season for Orthodox and Catholic Easter celebrations - the weather is so nice, but rates increase as it is a high demand period.

May till September is the summer season.  May and September weather is not so hot as indicated above, while June, July and August are so hot, but rates are really cheap for flights and also for accommodations.

It is advised that you try the safari trips in the western desert, where treasures of beauty might be found that nobody knows about and no one thought to explore. Desert safaris are perfect all year long, except it gets cold through winter, meaning from end of November till end of February.

Wishing all a nice trip!