Dry weather in the Southeast, rain in the Northeast: what to expect from autumn, which starts this Monday (20)

Autumn starts this Monday (20) at 6:25 pm, Brasilia time.

The season is defined as a moment of transition between the most humid and hot season, in summer, to the coldest and driest period, in winter.

Check out the main forecasts for each region of the country for the coming months.

Dry weather in the Southeast

At the Southeast , April starts with some typical summer rain showers, but as the month progresses, dry weather begins to predominate. Very high temperatures are not expected, especially in the interior of São Paulo and Minas Gerais, where temperatures are slightly below average

Cold air masses of weak to moderate intensity pass through the East of the region bringing temperature drops and inaugurating a typical autumn pattern. On the coastline of São Paulo and Rio de Janeiro, some extreme rainfall events may occur during the passage of cold fronts.

In May and June, dry weather predominates throughout the region, with very sunny days, a wide temperature range, which is the difference between the minimum and maximum temperatures recorded on the same day.

In addition, slightly below average peaks are expected between May and June in the interior of SP and MG. It rains a little above average in the south of the region, between SP and RJ, but with a predominance of sunny days. Cold air masses of moderate to strong intensity may arrive between May and June, but sharp drops in temperature will not be very frequent.

Hottest season in the South

The season begins with rains that are still irregular in time and space over a good part of the South region , mainly in Rio Grande do Sul, where April will still have above average temperatures. In April, rainfall volumes gradually increase over the region, and a more regular pattern should occur between May and June.

Every month tends to be a little warmer than normal in the South, but seasonality keeps temperatures mild. Large thermal variations are expected, with entry of some cold air masses of even strong intensity – mainly from May onwards – but alternating with slightly higher temperatures.

Northeast will have persistent cloudiness

At the North East , it rains a lot in April. Large volumes are expected in the North of the region until May, with a significant decrease in June. Temperatures, especially the maximum, are below average in this period due to persistent cloudiness.

East wave disturbances are present throughout the season and actively contribute to the presence of rain on the northeastern east coast. In June, these temperature deviations decrease and the heat increases over the region.

Rainfall in the Midwest

As the rains subside, temperatures are expected to rise in the Midwest throughout the autumn.

In April, typical summer rain showers still occur between the north of Mato Grosso and Goiás. In the second half of the month, days with firm weather predominate. The temperature is slightly below the average between the East of Mato Grosso, Goiás and the Federal District.

In May and June the weather is firm throughout the region on most days, except in the south and west of Mato Grosso do Sul, which can rain above average in this period due to the arrival of cold fronts.

The most accentuated drops in temperature can occur especially in Mato Grosso do Sul and Southwest of Mato Grosso. However, cold air inflows will not be frequent over the region. The temperature is above average between May and June in Mato Grosso, west of Goiás and north and west of Mato Grosso do Sul.

Floods in the rivers of the North region

The next month will be rainy in the north of the country, mainly in Pará and Tocantins, where volumes are above average. The temperature follows this trend, remaining below average in these areas, due to persistent rain, but maintaining a muggy weather condition.

In other areas, the temperature rises during autumn and is above average in Amazonas, Roraima, Rondônia and Acre.

Frequent seasonal rains raise the level of rivers in the Amazon Basin, causing river floods between June and July.

El Niño and the winter trend

A change in temperature conditions in the coming months could lead to the possible return of the El Niño phenomenon, according to the forecast of the World Meteorological Organization (WMO). In the last three years, the climate has been influenced by La Niña with rainfall patterns in different parts of the world.

The UN agency states that there is a 15% probability of El Niño returning between April and June. The odds rise to 35% between May and July. And they are 55% from June to August.

Known as an atmospheric phenomenon, El Niño causes unusual warming of the waters of the Pacific Ocean in the equatorial part, which in turn influences the water surface and the climate of other parts of the globe. The La Niña phenomenon is related to the reduction in the temperature of the Pacific waters also in the equatorial part.

In winter, El Niño consolidates and the trend is for temperatures slightly above average throughout most of the country, except in the interior of São Paulo, Minas Gerais and Bahia, regions without significant deviations, practically within normal limits.

In the South region, it follows the pattern of large thermal oscillations, due to the entry of cold air masses and warmer air from the interior of the country. Rain tends to be slightly above average in the South, in addition to parts of SP and in the West of MS and MT – especially in August.

In the Midwest and North, above-average temperatures and a predominance of dry weather. The temperature rises and is also slightly above average in the Northeast.

(With information from Climatempo)