Autumn 2023: Inmet presents forecast for the season

Autumn in the Southern Hemisphere began at 18:25 pm (Brasília time) on March 20, 2023. It will end at 11:58 am (Brasília time) on June 21. During this period, rainfall is scarcer in the interior, especially in the semi-arid northeast. This season is also characterized by incursions of cold air masses from the south of the continent that cause a decline in air temperatures, mainly in the South Region and part of the Southeast Region.

During the season, it is possible to observe the first formations of adverse phenomena, such as fogs in the South, Southeast and Central-West regions; frosts in the South and Southeast regions and in Mato Grosso do Sul; snow in the mountainous areas and plateaus of the South Region, and cold in the south of the North Region and in the states of Mato Grosso do Sul, Mato Grosso and even in the south of Goiás.

Inmet's forecast by regions for the April-May-June/2023 quarter is as follows:

• Midwest region: rainfall close to or above the climatological average in Mato Grosso and the extreme north of Mato Grosso do Sul. In other areas, rainfall is expected to vary between close to or below average. It is worth mentioning that, from May onwards, the dry period begins in the central part of the country. Temperatures are expected to be above average throughout the region, especially in the north of Goiás, where they can exceed 24 ºC;

• South region: below-average rainfall in much of Paraná and Santa Catarina, except in the east of these states, where rainfall may be close to average, due to the passage of cold fronts. Highlight is the forecast of the return of more frequent rains over Rio Grande do Sul, due to the weakening of the La Niña phenomenon, which hit the state for three consecutive years, causing a lack of rain. The air temperature in the South Region is expected to prevail above the climatology of the period, however, the possibility of frost cannot be ruled out, especially in mountainous areas, as winter approaches. On the coast of the region, rain may soften temperatures;

• Southeast region: below-average rainfall volumes over the next three months. As in the Central-West Region, there is normally a reduction in rainfall in this region as winter approaches, starting the dry period. The average air temperature should prevail close to and slightly above the climatology of the period, however, the possibility of the entry of cold air masses that could reduce temperatures on a few days in higher altitude locations, from the month of May onwards, cannot be ruled out;

• North region: Rainfall is expected to remain above the climatological average, with volumes that may exceed 800 millimeters (mm), mainly in areas of northeastern Pará and northwestern Amazonas due to the persistence of rainy days. In the south of Pará, the probabilities indicate rainfall slightly below average. The INMET forecast also indicates the predominance of temperatures close to and slightly above average in much of the North Region, with values ​​that may exceed 26 ºC;

• Northeast Region: above-average rainfall in much of the Northeast Region, and between the months of April and May, rainfall is expected to persist in areas further north due to the permanence of the Intertropical Convergence Zone (ZCIT), which may be located further south of its climatological position. Furthermore, warmer waters near the northeastern coast increase the chances of rain until late autumn. In the east of the Northeast, rainfall normally exceeds 400 mm in the quarter with the beginning of the rainy season. Temperatures will remain close to average, from the coast of Maranhão to Alagoas, however, in the interior of the northeast, the forecast is for higher temperatures.