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Irregular rain hits areas of the Midwest in early May, but Goiás, DF, and part of MS face drier weather and agricultural risk.
In April 2026, the National Institute of Meteorology (INMET) pointed to a climate transition scenario in the Midwest: rain still appears in areas of Mato Grosso and Mato Grosso do Sul, but is already losing strength in Goiás, the Federal District, and a large part of the central region of the country. The most specific forecast available indicates volumes above 60 mm between April 23 and May 9 in areas of northwestern and western Mato Grosso and south-central Mato Grosso do Sul, while other areas remain below 40 mm.
The alert does not mean widespread rain throughout the Midwest. On the contrary: the most concerning data is the irregularity. INMET itself reported, on April 27, 2026, that between April 27 and May 4, the entire central region exhibits a drier pattern, with accumulations of up to 40 mm only in northwestern Mato Grosso and southern Mato Grosso do Sul, while Goiás, the Federal District, and other areas of MS have predominantly stable weather and minimal chances of light and isolated rain.
Next, understand why this rain in the center of the country does not eliminate the risk of drought in the fields, which areas can still receive significant accumulations, and why early May marks a decisive turning point for the second crop.
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Irregular Rain in the Midwest Raises Alert Because It Arrives in Patches and Does Not Resolve the Advance of Dry Weather
The central point of the forecast is not a large, widespread storm covering the entire Midwest, but the formation of an irregular band of instability in specific parts of the region.
INMET reports that the largest accumulations predicted for the fifteen days between April 23 and May 9 are concentrated in northwestern and western Mato Grosso and south-central Mato Grosso do Sul, with volumes above 60 mm. In other areas of the region, accumulations are expected to remain below 40 mm between late April and early May.
This completely changes the interpretation of the alert. It is not about voluminous and homogeneous rain across the entire center of the country.
The forecast indicates an unequal distribution, with some areas receiving enough rain to temporarily relieve the soil and others practically entering the transition to the dry season. This difference is decisive for agriculture, because second-crop plantations may be in phases sensitive to water stress precisely when the rain begins to fail.
In the weekly bulletin released on April 27, INMET reinforced this pattern by stating that the forecast for accumulated rain between April 27 and May 4, 2026 shows larger volumes in the North, Northeast, and, to a lesser extent, the South-Central, while the central region exhibits a dry pattern. For the Midwest, the agency points to irregular rain of up to 40 mm in seven days in northwestern Mato Grosso and southern Mato Grosso do Sul.
Mato Grosso and Mato Grosso do Sul Concentrate the Largest Predicted Accumulations in the Center of the Country
Within the Midwest, Mato Grosso appears as one of the areas with the highest chance of receiving significant rain in early May. INMET’s forecast cites accumulations above 60 mm in the northwest and west of the state between April 23 and May 9, while the weekly bulletin indicates up to 40 mm in seven days in northwestern MT between April 27 and May 4.
In Mato Grosso do Sul, the highlight is the south-central and southern parts of the state. INMET states that south-central MS could record accumulations above 60 mm over the fifteen-day period, while the weekly bulletin points to up to 40 mm in seven days for southern Mato Grosso do Sul.
At the same time, the agency warns that areas of MS itself continue to have relative humidity below 40%, especially in parts of the state, which maintains the risk of soil water loss.
Goiás and Federal District Enter the Driest Stretch of the Forecast While Crops Demand Water
The scenario is more delicate in Goiás and the Federal District. INMET reports that volumes below 10 mm or even absence of rain may occur in southeastern Mato Grosso, Goiás, and the DF in the interval between April 23 and May 9.
This data is especially relevant because the region was already being monitored for risk of water stress in second-crop cultures.
In an analysis published on April 15, 2026, INMET had already warned that the reduction in rainfall in April increased the risk of loss for second-crop cultures in the Midwest and Southeast. The agency cited the transition from the rainy season to the dry season and highlighted that crops such as corn, beans, and cotton increase water demand during vegetative and reproductive phases.
In the case of Goiás, the situation requires attention because part of the crops still depends on previously accumulated soil moisture. INMET reports that, despite the reduction in rainfall in recent weeks, the moisture still present in the soil contributed to the development of second-crop corn fields in a large part of the state.
However, the scenario shows signs of change, especially in the southern and eastern regions, where the combination of low accumulated rainfall and high temperatures tends to intensify soil water loss.
The agricultural alert is stronger in Rio Verde, in southern Goiás. According to SISDAGRO estimates cited by INMET, there was an increase in water deficit starting in March, with impacts on the productive potential of second-crop corn and an estimated loss of 52.6% in the period analyzed by the system.
Rain until early May does not eliminate the risk of water deficit in second-crop corn fields
The rain predicted for parts of the country’s center should not be read as a sign of complete normalization. INMET itself states that the forecast for the next fifteen days indicates irregularity in the distribution of rainfall in the Midwest Region. This means that some municipalities may record significant accumulations, while nearby areas remain with weak, isolated, or absent rain.
This irregularity precisely affects a critical phase for second-crop corn. The agency explains that crops in flowering and grain-filling stages require greater water demand. When water restriction appears at this moment, development can be directly affected, with damage to grain formation and weight.
In Mato Grosso do Sul, the main point of attention is in areas of the southwest and south of the state. INMET reports that the combination of low rainfall volumes and high temperatures has contributed to the reduction of soil water reserves. In Dourados, SISDAGRO estimates indicate a persistent water deficit throughout the cycle, reflecting an increase in the loss of productive potential for second-crop corn.
High temperatures and humidity below 40% worsen the impact of poorly distributed rain
Another factor weighing on the alert is temperature. INMET forecasts maximums between 26 °C and 34 °C in most of the Midwest throughout the analyzed weeks. In areas of northwest and north of Goiás, northeast and south of Mato Grosso, values may exceed 34 °C.
High temperature increases evapotranspiration, a process by which water returns to the atmosphere through soil evaporation and plant transpiration. In practice, even when there is localized rain, part of the moisture can be quickly lost if heat, wind, and low humidity dominate the following days. Therefore, isolated accumulations do not always reverse the water deficit in crops.
Relative air humidity also draws attention. INMET indicates that it should remain below 40%, especially in eastern and southern Goiás, as well as in areas of Mato Grosso do Sul. The agency states that this scenario favors the reduction of soil water reserves throughout the week, with the persistence of water deficit in the region.
April marked the transition from the rainy season to the dry season in central Brazil
The behavior predicted for early May does not arise in isolation. It is part of the typical transition from the end of the rainy season to the dry season in Central Brazil.
In a publication on April 15, INMET reported that the reduction in rainfall volumes in the following days indicated the advance of this transition period, with a direct impact on second-crop cultures.
In the same report, the agency stated that the forecast indicated volumes below 30 mm in a large part of Minas Gerais and Goiás during the analyzed period, with more restricted rainfall in some areas. In Goiás, the highest predicted accumulations were in the eastern and northern regions, between 30 mm and 70 mm, while southern Goiás would have isolated rains and low volumes, between 7 mm and 20 mm.
This data helps explain why the Midwest goes on alert even when part of the region still registers rain. The problem is not just the total absence of precipitation, but the change in regime. Rainfall ceases to be frequent, starts to occur in more spaced-out events, and concentrates in smaller areas, which complicates agricultural planning and increases dependence on constant meteorological updates.
In the Southeast, especially in Minas Gerais, INMET’s analysis also indicated a reduction in rainfall in a large part of the state, with volumes below 10 mm in the north-central region and rainfall more restricted to the south, northwest, and Triângulo Mineiro, with accumulations between 30 mm and 50 mm.
El Niño forming may alter rainfall patterns in the coming months, but it doesn’t solely explain the current alert
The beginning of May also occurs in a context of attention for the Equatorial Pacific. On April 24, 2026, INMET reported that recent forecasts indicated an increased probability of El Niño formation throughout 2026.
According to the agency, based on the CPC/NOAA bulletin issued on April 20, the La Niña phase had ended, and neutrality was in effect in the central Equatorial Pacific, with an 80% chance of persistence until the end of the first semester.
For the June-July-August quarter, INMET reports a 79% probability of El Niño establishment, rising to over 80% in the July-August-September quarter. From the August-September-October quarter onwards, the chance of the phenomenon’s establishment is equal to or greater than 90%, with the possibility of persistence until next year.
Climatempo also describes an autumn of 2026 with rain lasting longer than normal in some areas and with frequent showers in April in the Southeast and Midwest.
However, the company indicates that the weather begins to dry and cool in the second half of May, while moisture transport from the Amazon can still maintain showers for longer in parts of the Midwest and Southeast.
The impact on agriculture is concentrated on the second crop and soil management
The greatest practical impact of the forecast is in the field. INMET links the irregularity of rainfall and high temperatures to the development of the second corn crop in the Midwest, with special attention to Goiás and Mato Grosso do Sul.
The agency states that water restriction can affect the formation and weight of grains when it occurs during critical phases of the crop.
This risk is not limited to corn. In a previous analysis, INMET also cited cotton and beans among the crops sensitive to reduced rainfall in the Midwest and Southeast. For corn, impacts include reduced leaf area and damage to pollination; for beans, effects related to flower abortion and low pod setting may occur; for cotton, an early decrease in rainfall tends to reduce the emission of productive branches and flower buds.
The most concerning data is that dry weather does not act alone. It combines with heat, low humidity, and sensitive phenological phases.
When these factors occur together, the crop can lose productive potential even without a formally declared extreme drought. This is the type of risk that usually appears first in soil water balance indicators, before turning into consolidated harvest loss.
INMET’s recommendation, in its agroclimatic analysis, is to continuously monitor meteorological updates and soil moisture conditions to support management decisions, reduce operational risks, and optimize the planning of field operations.
Let us know in the comments if, in your region, the rain is still coming strong or if the dry weather has already started to dominate earlier than expected.
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