Tropical Storm Mario forms, heavy rainfall forecast for southern Mexico
Tropical Storm Mario formed at 15:00 UTC on September 12, 2025, just off the coast of Mexico, prompting the government of Mexico to issue a Tropical Storm Watch from Lazaro Cardenas to Punta San Telmo. At the time of formation, the center of Mario was located 65 km (40 miles) SSW of Zihuatanejo and 95 km (60 miles) SSE of Lazaro Cardenas, Mexico.
Satellite image of Tropical Storm Mario at 18:10 UTC on September 12, 2025. Credit: NOAA/GOES-East, RAMMB/CIRA, The Watchers
- Although Mario is a small tropical storm, heavy rainfall will impact southern Mexico through Sunday, which could result in flash flooding, particularly in areas of higher terrain.
- Tropical storm conditions are possible along portions of the coast of Michoacan today while Mario moves roughly parallel to the southwestern coast of Mexico.
- Gusty winds are possible elsewhere along the coasts of western Guerrero, Michoacan, and Colima through tonight.
At 18:00 UTC (12:00 CST), Mario’s center was located about 130 km (80 miles) WSW of Zihuatanejo and 90 km (55 miles) SW of Lazaro Cardenas. It had maximum sustained winds of 65 km/h (40 mph) and minimum central pressure of 1006 hPa. The storm was moving WNW at a speed of 22 km/h (14 mph).
Mario is a tiny tropical storm, with tropical-storm-force winds extending outward up to 35 km (25 miles) to the north of the center.
Tropical Storm Watch remains in effect for Lazaro Cardenas to Punta San Telmo where tropical storm conditions are possible within 12 hours.
Interests elsewhere along the coast of southwestern Mexico should monitor the progress of Mario, the National Weather Service (NHC) warns.
NHC forecasts Mario to move roughly parallel to the coast of Mexico through tonight, and then begin to move farther away from the coast on Saturday, September 13.
Mario is expected to produce rainfall totals of 50 to 100 mm (2 to 4 inches), with local amounts up to 150 mm (6 inches), across southern Mexico through Sunday. This brings a risk of flash flooding, particularly in areas of higher terrain.
References:
1 Tropical Storm Mario Intermediate Advisory Number 4A – NWS/NHC – 18:00 UTC on September 12, 2025
I'm a dedicated researcher, journalist, and editor at The Watchers. With over 20 years of experience in the media industry, I specialize in hard science news, focusing on extreme weather, seismic and volcanic activity, space weather, and astronomy, including near-Earth objects and planetary defense strategies. You can reach me at teo /at/ watchers.news.
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