Map from Google - Qatar

The climate of Qatar is desert, with a very mild winter, and a very hot and sunny summer. Being a small and flat country, it has a uniform climate throughout the territory.
Basically there are two main seasons: a cooler season from December to February, and a hot season from April to October, within which we can distinguish a very hot period from May to mid-October. March and November are transitional months, hot but without excesses.
In Doha, the daily average temperature goes from 18.5 degrees Celsius (65 °F) in January, to 37 °C (99 °F) in July. Here are the average temperatures of Doha.
Average temperatures - Doha
Min (°C)141618232830323129262217
Max (°C)222429344042434239363025
Min (°F)576164738286908884797263
Max (°F)72758493104108109108102978677

The prevailing wind is moist and blows from the north-west, more frequently in the summer months. Another wind, hot and dry, can blow throughout the year, but preferably in spring; it blows from the south and it's able to raise the temperature to about 30 °C (86 °F) in winter and to about 40 °C (104 °F) and above from April to October, while drastically lowering relative humidity; it is also able to raise dust and sand storms.
The scarce rainfall occurs during the winter months, and it amounts to less than 100 millimetres (4 inches) per year. Every now and then, some rains may occur also in spring, in March, April and even May, while in summer it never rains. The rains in Qatar occur in the form of brief but sometimes heavy showers, which can sometimes fill the wadis, the river beds which remain dry most of the year, and cause even flooding.
Here is the average precipitation in the capital Doha.
Average precipitation - Doha
Prec. (mm)131716940000131275

In winter, from December to February, temperatures are mild and the sky is often clear, so it's a spring-like season. Lows are around 14/17 °C (57/63 °F), and highs around 22/25 °C (72/77 °F). However, there can be some cool and windy days, especially in January, in which the temperature drops below 10 °C (50 °F) at night, and remains around 15/16 °C (59/61 °F) in the afternoon.
Summer is very hot, with highs around 42/43 °C (108/109 °F) from June to August, and lows around 30/32 °C (86/89 °F). There are torrid days, in which the wind from the inland desert prevails, so that the daytime temperatures rise above 40 °C (104 °F), and sometimes even 45/47 °C (113/117 °F), while other periods are less hot but more humid, with highs around 37/38 °C (99/100 °F), and a sweltering heat. Over the course of the summer months, the relative humidity gradually increases, so that the second part of the season, in August and September, is particularly stifling. The combination of moisture and temperature that is observed in summer in the countries of the Persian Gulf, is actually one of the worst in the world.


In Qatar the sun shines all year round, sometimes however some cloud banks can pass even in summer.
Sunshine - Doha
Sun (hours)888910111011101098

The sea in Qatar is a bit cool from January to March, particularly in February, when it reaches the lowest temperature, about 20 °C (68 °F), while it's still quite warm in December, when it's about 24 °C (75 °F). In summer, the waters of the Persian Gulf become very warm, exceeding 30 °C (86 °F) from June to October.
Sea temperature - Doha
Sea (°C)222021232730323333312824
Sea (°F)726870738186909191888275

When to go

The best time to visit Qatar runs from mid-November to mid-March: it is the only time of the year which is not hot. In general, the weather is mild and sunny from December to February, warm but not too much in November and March. Some cloudy days are possible, sometimes with rain, especially from December to February.

What to pack

In winter: light clothes for the day, sweater and jacket for the evening and for cool days, scarf for the wind.
In summer: lightweight clothes, made of natural fabric (cotton or linen), desert turban, sweatshirt and scarf for air conditioned places. For women, it is better to avoid shorts and miniskirts outside of tourist resorts.
For the reef, snorkeling equipment, water shoes or rubber soled shoes.