Brazil's National Institute of Meteorology (INMET) placed 15 states under yellow storm alerts for October 21 and 22, 2026, as a new rain system moved from the South region into the Center-West, Southeast and parts of the North, according to the agency's own forecast bulletin and reporting by regional outlet dgabc.com.br.
The alerts, INMET's lowest of three severity tiers (yellow, orange and red), warn of rainfall between 20 and 30 millimeters per hour, or up to 50 mm over a day, along with winds of 40 to 60 km/h and hail in some areas, dgabc.com.br reported citing the institute's bulletin. INMET lists the associated risks as power outages, crop damage, fallen branches and localized flooding, though it classifies that risk as low.
Which states are covered
According to the INMET bulletin reported by dgabc.com.br, the Thursday, October 22 alert spans Acre, Amazonas, Espírito Santo, Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Pará, Paraná, Rio de Janeiro, Rio Grande do Sul, Rondônia, Roraima, Santa Catarina and São Paulo, including the São Paulo metropolitan area. A separate, narrower alert for Wednesday, October 21, running from 3 p.m. to 11:59 p.m., covers Mato Grosso do Sul, Paraná, Santa Catarina and Rio Grande do Sul.
INMET's own forecast notice for the two days, published on its portal, said the South region would see the heaviest activity, with storms moving into western Rio Grande do Sul, Santa Catarina and Paraná on Wednesday and spreading across all three states on Thursday. The Center-West, led by northwest Mato Grosso, and the Southeast, particularly eastern São Paulo, were forecast to see thunderstorms expand on Thursday. Acre and Rondônia in the North faced persistent rain with a yellow alert already on Wednesday, with Amazonas joining the broader alert on Thursday. The Northeast, by contrast, was expected to stay dry, with INMET flagging low-humidity conditions in interior areas instead.
South region faces the longest exposure
Paraná is covered by both alert windows: the Wednesday-afternoon regional alert alongside Mato Grosso do Sul, Santa Catarina and Rio Grande do Sul, and the broader 15-state alert on Thursday, according to INMET's bulletin as reported by dgabc.com.br. Both windows carry the same forecast parameters for the state: rain of up to 50 mm per day, winds of 40 to 60 km/h and possible hail.
In Rio Grande do Sul, INMET's yellow alert for Wednesday afternoon covers the Missões, Northwest and parts of the North and Fronteira Oeste regions, forecasting up to 50 mm of rain, winds up to 60 km/h and possible hail, according to Jornal Timoneiro's report citing the institute. The outlet said instability was expected to advance into western and northwestern parts of the state on Thursday, with rainfall potentially exceeding 70 mm in the Northwest region by Friday, October 23. A separate yellow alert specifically for Caxias do Sul and the state's northeast, valid all day Thursday, October 22, forecasts winds up to 60 km/h, hail and up to 50 mm of daily rain, O Tempo reported, noting INMET itself describes the associated flooding and power-outage risk as low under this alert level.
Earlier storm system in early October
The current alerts follow a separate, more intense storm system in the same region earlier in the month. A report by Exame, dated October 8, described yellow and orange alerts for Rio Grande do Sul with wind gusts exceeding 90 km/h, hail and forecasts of rainfall reaching up to 200 mm in 24 hours in parts of the state, tied to a low-pressure system and an extratropical cyclone forming off the coast of Argentina and Uruguay. Santa Catarina was also under an orange alert and Paraná under a yellow alert in that episode. That system is distinct from the October 21–22 alerts and involved higher alert levels (orange) than the current yellow-level warnings.
What officials and broadcasters are saying
Brazil's public broadcaster Agência Brasil flagged the broader pattern in an October 21 radio segment titled "Chuvas e tempestades avançam pelo Brasil a partir de quarta," reporting that rain and storms were advancing across the country starting that Wednesday, consistent with INMET's own bulletins about the front moving from the South into the Center-West and Southeast.
INMET storm-alert snapshot by state cluster, Oct 21–22, 2026| Area | Alert window | Rain forecast | Wind/hail risk |
|---|
| Rio Grande do Sul, Santa Catarina, Paraná, Mato Grosso do Sul | Oct 21, 15:00–23:59 | up to 50 mm/day | winds to 60 km/h, hail possible |
|---|
| 15 states incl. São Paulo, Minas Gerais, Rio de Janeiro, Goiás | Oct 22, 00:00–23:59 | 20–30 mm/h or up to 50 mm/day | winds 40–60 km/h, hail |
|---|
| Northwest Rio Grande do Sul (Missões/Northwest) | Through Oct 23 | up to 70 mm (by Fri.) | winds to 60 km/h, hail |
|---|
What is still unclear
INMET's yellow-level alerts describe flooding and power-outage risks as low. No casualties, evacuations or infrastructure damage had been officially reported by INMET, Agência Brasil or the regional outlets reviewed as of October 21.
Questions
- Which Brazilian states are under storm alert this week?
- INMET's October 22 yellow alert covers 15 states: Acre, Amazonas, Espírito Santo, Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Pará, Paraná, Rio de Janeiro, Rio Grande do Sul, Rondônia, Roraima, Santa Catarina and São Paulo. A narrower alert for October 21 covers Mato Grosso do Sul, Paraná, Santa Catarina and Rio Grande do Sul.
- How much rain is forecast?
- INMET's bulletins point to 20–30 mm per hour or up to 50 mm per day in most alerted areas, with northwest Rio Grande do Sul potentially exceeding 70 mm by Friday, October 23.
- Is this the same storm system as the one in early October?
- No. A separate Rio Grande do Sul storm system around October 8, reported by Exame, carried orange alerts, gusts over 90 km/h and forecasts of up to 200 mm in 24 hours tied to an extratropical cyclone off Argentina and Uruguay, a more severe event than the yellow-level alerts now in place for October 21–22.
- What alert level is in effect, and what does it mean?
- The current warnings are INMET's yellow level, the lowest of three (yellow, orange, red), indicating conditions that require attention but, per the institute's own classification cited by regional outlets, a comparatively low risk of flooding or major disruption.
- Which region of Brazil is expected to stay dry?
- According to INMET's forecast notice, the Northeast region was expected to see stable, dry weather during this period, with the institute instead warning about low humidity in interior areas rather than rain.
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