Heavy rains in Michoacán, Guerrero, Oaxaca, and Chiapas are driving urgent alerts across southwestern Mexico on August 4, 2025, with authorities warning that thunderstorm activity, flooding, landslides, and reduced visibility will strain travel and local infrastructure. The National Meteorological Service says the combination of the Mexican monsoon, atmospheric instability, and a low-pressure channel is fueling very heavy rainfall in those four states, while heat waves bake parts of the north and northwest of the country.
In the most affected zones—Michoacán, Guerrero, Oaxaca, and Chiapas—forecast amounts qualify as heavy to very heavy, ranging from 50 to 75 millimeters, with storms carrying lightning and possible hail. Officials caution that these downpours can trigger sudden water accumulation on roads, rapid rises in rivers and streams, localized flooding, landslides in steeper terrain, and significant visibility reduction for drivers. Strong gusts accompanying storm cells also carry the risk of toppling trees and billboards.
The broader weather pattern includes another low-pressure channel over southeastern Mexico interacting with the approaching Tropical Wave Number 20 across the Yucatán Peninsula, reinforcing convection and rainfall potential. Meanwhile, Tropical Depression Eight-E formed early Monday in the Pacific Ocean but, according to meteorological bulletins, poses no direct threat to the country’s coasts at this time.
Outside the storm clusters, a heat wave persists in parts of Baja California, Baja California Sur, and Sonora, with temperatures soaring above 45°C in northeastern Baja California and northwestern and western Sonora. Hot to very hot conditions are forecast elsewhere along the Pacific coast, the Gulf of Mexico coast, and the Yucatán Peninsula.
Regional outlook and impacts
In the Valley of Mexico, partly cloudy to cloudy skies will give way to afternoon showers and thunderstorms in Mexico City and the State of Mexico, potentially accompanied by localized downpours and lightning. Morning fog banks are expected in higher elevations, with low temperatures dipping into the low teens Celsius in the capital and single digits around Toluca. Winds will be light to moderate, and rainfall could further suppress visibility in the afternoon.
On the Baja California Peninsula, extremely hot conditions prevail in northeastern Baja California and very hot conditions in southern Baja California Sur, with a continuing heat wave. Skies will be mostly clear in Baja California, while isolated showers may appear in Baja California Sur. Localized dust storms remain possible, especially with sustained northwesterly winds gusting up to 60 km/h in the Gulf of California.
The North Pacific region will see intense heating in parts of Sonora and Sinaloa, but also scattered thunderstorms with heavy rain, especially in areas under the monsoon influence. Flash flooding and runoff hazards accompany these afternoon storms, with winds from the west and southwest gusting into the 40 to 60 km/h range.
Across the Central and South Pacific, the heaviest precipitation is focused in Michoacán, Guerrero, Oaxaca and Chiapas, where very heavy rainfall and thunderstorms can rapidly elevate water levels in rivers and streams. Coastal areas should also prepare for choppy seas, with waves from 1.5 to 2.5 meters threatening surf zones and nearshore operations.
The Gulf of Mexico corridor will experience heavy rain and thunderstorms in southern Veracruz and Tabasco, while Tamaulipas sees hot to very hot temperatures mixed with shower activity. Gusty east-southeast winds up to 70 km/h in Tamaulipas could exacerbate localized hazards, especially in areas already saturated from prior rainfall.
On the Yucatán Peninsula, afternoon storms centered over Campeche and Quintana Roo will bring heavy rains capable of causing temporary flooding and reduced visibility, while Yucatán proper sees more scattered showers. Winds remain steady from the east and southeast with gust potential.
The Northern Tableland will have warm to hot afternoons, with heavy rains expected in Chihuahua and Durango. Isolated showers and thunderstorms will also affect Nuevo León, San Luis Potosí, and Zacatecas, with strong wind gusts in storm cells potentially disrupting travel.
On the Central Plateau, heavy rain is concentrated over Puebla with accompanying hazards similar to other mountainous zones—rising streams, landslides, and poor road visibility. Surrounding states like Morelos and Guanajuato will see showers, while higher elevations could experience cooler early-morning temperatures below 5°C.
What residents and travelers need to know
Authorities are urging people in affected areas to avoid driving through flooded stretches, secure loose outdoor items, and stay updated through official channels. Urban drainage systems may be overwhelmed in short bursts of rain, and rural communities in mountainous terrain should be ready to respond to landslide warnings. Those in heat-wave zones should stay hydrated and limit exposure during peak afternoon heat, especially in Baja California and Sonora where temperatures exceed 45°C. N+
Emergency services and local governments are on alert, especially in regions with a history of rapid runoff and urban flooding. Travelers should allow extra time, monitor road conditions, and expect possible interruptions to outdoor plans.
Background context
The Mexican monsoon, enhanced by regional low-pressure systems and moisture surges from the Gulf of Mexico, typically peaks in summer and brings both critical rainfall and flash-flood risks across western and southern Mexico. This year’s pattern aligns with broader seasonal expectations, even as localized heat waves strain public health in northern states.
Local emergency agencies advise keeping emergency kits ready, avoiding river crossings during storms, and following instructions from civil protection authorities. Residents in mountainous zones should be particularly cautious during overnight and early-morning rain events, when saturation increases landslide likelihood.
Conclusion
Heavy rains in Michoacán, Guerrero, Oaxaca, and Chiapas mark the most urgent weather threat for August 4, 2025, while heat and dryness persist elsewhere, creating a sharp regional contrast. Preparedness and cautious behavior during storms will be key to minimizing injuries, infrastructure damage and travel disruption over the next 24 to 48 hours.
