Sudan experiences mean annual temperatures between 26°C and 32°C, with summer temperatures in the north often exceeding 43°C. Rainfall in Sudan is unreliable and erratic, with great variation experienced between northern and southern regions. Northern regions typically experience virtually no rainfall (less than 50 mm annually), central regions receive between 200 mm and 700 mm per year, and some southern regions experience more than 1,500 mm annually. Most rainfall occurs during the rainy season from March to October, with greatest concentration between June and September. Key historical climate trends are summarized below:

Temperature

• Air temperatures in Sudan have been steadily increasing over the period 1960 – 2009, with temperatures in the 2000 – 2009 period between 0.8°C and 1.6°C warmer than they were in the 1960 – 1969 period.
• Increases of between 0.2°C and 0.4°C per decade in the periods March to June and June to September were experienced from 1960 – 2009.
• Rising temperature trends have also increased the rates of evaporation and the likelihood of drought events.

Precipitation

• From 1941 to 2000, average annual rainfall has declined from about 425 mm/year to about 360 mm/year, a decrease of annual rainfall of about 0.5% per year; and the coefficient of variability of rainfall shows an overall increasing trend, suggesting greater rainfall unreliability.
• Annual variability in rainfall is most serious in the arid northern parts of the country where the average variability now exceeds 100% and, at the national level, greater rainfall variability is increasing at a rate of about 0.2% per year.
• Variation within years has seen annual dry season rainfall totals increasing 20-30mm per decade in the extreme north and south, while annual rainy season rainfall totals have been decreasing by 10–30 mm per decade, primarily in the west.

This section provides the options to visualize historical climate data for different timeframes via map and annual cycle chart.