Before I moved to Saudi-Arabia I assumed the weather would mostly be hot and dry all year round without much variations. But I've come to realize there are in fact different periods in the year which could be defined as seasons, but very different to the ones we are used to in Finland or elsewhere in the western world. These following seasons would be more typical in Riyadh than in Jeddah where the climate is very humid year round.
The cold, rainy season
Characteristics for this season are the "cold" weather ranging anywhere between near zero in the mornings to +20c during the day. There might be heavy showers or occasional light rain but typically they won't last more than a few days at a time. This is the best time to visit the desert which will be blooming with green scenery and flowers after the rains. Begins usually around December lasting until February.
The sandstorm season
This is the worst time of the year in my opinion. It starts around February to March lasting until May-June. Saudi-Arabia is ridden with sandstorms from mild to moderate or severe with total lack of visibilty. Sometimes they come with thunderstorms, hail or rains mixed with dust resulting in muddy rain. The temperatures start rising eventually topping +40c at the end of the season.
The hot season
From around May up until October the mercury will not drop below +40c. This season is when most people want to leave the country. The dry heat might rise up to +50c degrees in the worst months and typically the nights will not bring much relief to the scorching heat.
The mild, clear season
This is my favorite season, although it usually doesn't last long, the weather is perfect from around October to the end of November. There are typically very clear skies with no sandstorms and the temperatures hover around a lovely +30c. Reminds me of weather on a perfect Finnish summer day, which we might be lucky to get a few times in a year!