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May 6, 2014

Dry Season Taking hold in Southeastern and Central Brazil

After an off-and-on rainy season in southeastern Brazil, it looks now like the annual dry season is starting to take hold. The last significant rainfall in the city of Sao Paulo for example occurred 20 days ago and local meteorologist feel there will be limited chances of rainfall going forward. The longest previous dry spell this year was 15 days without rainfall at the end of January and early February. A similar situation is developing in northeastern Brazil and westward into central Brazil as well. In areas of the state of Tocantins the relatively humidity has dropped to 20% and parts of Mato Grosso saw their last significant rainfall in mid-April.

The dryer weather is the result of a high pressure moving into eastern Brazil from the southern Atlantic Ocean. The high pressure keeps moisture from the Amazon region from moving into central and eastern Brazil resulting in clear skies, light winds, and low relative humidity. Once the dry weather strengthens its hold on the region, a return of the rains would not be expected until August or September.

The dryer weather is also increasing chances of fires all across central Brazil. In the state of Sao Paulo for example, there have been 414 fires during the period from January 1st through May 5th, which is 76 more than the same period last year and the most in five years.

The lack of rainfall and light winds also allows the buildup of pollution in urban areas which was the primary reason why the burring of sugarcane fields before harvesting is now being phased out across southeastern Brazil. The dry leaves were traditionally burned off in order to facilitate hand-harvesting. Now that burning is being phased out, mechanical harvesting of the sugarcane is quickly replacing hand harvesting.

The onset of dryer weather is not good news for the low water levels in many hydroelectric reservoirs in southeastern Brazil. The region suffered under a severe drought from December to early February at a time when the reservoirs should have been refilling. Instead, the water levels continued to drop during the summer months and now there are fears of electrical shortages during the dry season.