The climate in Dourados in 2021: report of an atypical year

The year 2021 was difficult for the vast majority of people. Among the many difficulties faced, we can undoubtedly also include the climate issue. This was the case of the climate in Dourados, MS, which in 2021 showed completely atypical behavior, with droughts, poorly distributed rainfall, very hot periods and a cold winter. Much of this atypical behavior can be attributed to the influence of La Niña, a climatic phenomenon, active from January to May and from August to December, that is, practically throughout 2021. Analyzing the Monthly Agrometeorological bulletins from the Guia Clima system, we can check how the weather behaved in Dourados throughout 2021.

The year started with a lot of rain. January 2021 was the wettest in the 43-year meteorological series by Embrapa Agropecuária Oeste de Dourados. It rained 345 mm; more than double the average.

However, after this extremely rainy January, the first drought of the year began, a period of four months, with scarce and poorly distributed rain.

In February it rained only 47 mm in Dourados and in March 40 mm, 30% of the average for those months. The drought continued in April and May, months in which it rained, respectively, only 37 mm and 36 mm, i.e. 35% and 34% of the historical average.

Based on the historical series, from February to May it is expected that it will rain around 500 mm. However, in 2021 it only rained 160 mm, that is, a third of what was expected. From February 17th to May 31st, for 120 days, the soils of Dourados had unsatisfactory moisture levels.

After this drought, the rains returned in June. Concentrated in the first ten days of the month, rainfall totaled 133 mm, almost double the average.

The month of June started with high temperatures, but with the entry of a polar mass into the region, very low temperatures occurred. In the last two days of the month there was frost formation.

July 2021 was the coldest in the last 14 years in Dourados. The intense cold was caused by the entry of three polar masses into the region. In six days there was frost formation. Furthermore, there was no rain in the month of July.

August, unlike July, had very high temperatures. It was the hottest August in the last six years. Rain only occurred at the end of the month and totaled 46 mm, practically equal to the average.

High temperatures continued and September 2021 was the hottest September in the 43-year historical series. Furthermore, rainfall was scarce, totaling 49 mm, half the average.

In the months of July, August and September, there is normally a reduction in rainfall, one of the characteristics of the region's dry winter. But in 2021 this reduction in rainfall was even greater. Around 200 mm of rain is expected over these three months. However, in 2021 it only rained 95 mm, less than half of what was expected. During this period of 92 days, the soils of Dourados remained with unsatisfactory moisture levels for 80 days.

After the second drought of the year, significant rains occurred in October. It rained more than 100 mm above the month's average and, due to frequent rains, temperatures were milder.

However, as was the case in most previous months, rain was scarce in November. In 2021, November was the month with the lowest rainfall in the historical series. It only rained 47 mm, 30% of the average.

At the end of 2021, the hottest December in the last 36 years occurred in Dourados. Rain remained scarce and poorly distributed. It rained just 68 mm in December, 39% of the average

In November and December, late spring and early summer, significant rainfall is expected, close to 330 mm. But in 2021 the third drought of the year occurred. It only rained 115 mm, approximately a third of what was expected. In the 61 days of November and December, the soils remained with unsatisfactory moisture levels for 53 days.

There was a predominance of temperatures above average in 2021 in Dourados, despite the occurrence of some periods of intense cold in the months of June and, mainly, July. As a consequence, the average annual temperature in 2021 was 23,4 °C, three tenths of a degree higher than the historical average, which is 23,1 °C.

The average annual rainfall in Dourados is 1400 mm. In 2021 it rained only 1109 mm, almost 300 mm less than the average. It was the year with the lowest rainfall since 2001. It is noteworthy that in the last three years, since 2019, the annual rainfall total has been lower than the historical average.