Roller Coaster Week of Weather for Argentina, Paraguay

By Dan DePodwin, Meteorologist

September 9,2013; 9:14PM,EDT

 

 

A roller coaster week of weather is in store for Argentina, Paraguay, Uruguay and southern Brazil. Featuring extreme heat, a rapid cooldown and bouts of rain, the week will be changeable to say the least in many areas of southern South America.
As the start of spring approaches in the Southern Hemisphere, a taste of summer weather will be found from Argentina to southern Brazil as unusually warm weather builds across the southern part of the continent. A flow of sultry, tropical air from the north will allow temperatures to climb into the 30s Celsius (mid-80s to near 100 Fahrenheit) in many places through at least the middle of the week. Specifically, Buenos Aires, Argentina, will peak at 32C (90F) on Tuesday, 14C (8F) above normal!
A string of days above 32C is expected to bake Asuncion, Paraguay, for the entire week with blazing sunshine. While this heat is not as unusual in Paraguay this time of year, the persistent warm weather along with warm nights will make for uncomfortable conditions.
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A cold front slicing northward will put an end to heat from south to north during the second half of the week. Temperatures will be on the downward trend in Buenos Aires starting Wednesday with the chilliest air arriving Friday when temperatures are expected to hold near 13C (55F)--about 20C lower than Tuesday!
The cool air will take longer to arrive in Asuncion but by Sunday, temperatures should fall to 18C (64F). Residents of Paraguay will notice a sharp contrast by the end of the weekend as temperatures go from 5-10C above normal to 5-10C below average.
Rainy periods will accompany the blast of cooler conditions. The rain is good news for many places in Argentina that have been parched recently. Buenos Aires did receive flooding downpours the over the weekend but wet weather was nearly absent in August. Cordoba, Argentina, has had less than 3 mm (0.10 of an inch) of rain since the beginning of July.
At this point, flooding does not look to be a major concern. Instead, a soaking rain is likely in northern Argentina, Uruguay, Paraguay and far-southern Brazil.
The chill will be reinforced late in the weekend and next week and it may even get cold enough for some places in the northern half of Argentina to experience a frost or freeze Sunday night and Monday morning.
While the cooldown will bring relief from the heat, the potential for a frost or freeze is not good news for the wheat crop. According to AccuWeather.com Expert Senior Meteorologist Jason Nicholls, "The wheat has entered its reproductive phase and a frost or freeze at this point in its growing cycle could hinder the growth of the crop."