Heavy rainfall brought by Hurricane Hilary has caused flooding in parts of western Mexico, where the storm has been blamed for two fatalities.

Mexico’s meteorological agency Servicio Meteorológico Nacional (SMN) reported significant rainfall in Sinaloa, Jalisco, Colima and Oaxaca over the last few days. Ina 24-hour period from 17 to 18 August, 76 mm of rain fell in Tortugas, Mazatlán in Sinaloa State. The following day El Triunfo in Baja California Sur recorded 76 mm; Huáscato in Jalisco recorded 92.5 mm; Isla Socorro in Colima saw 106 mm; and Zapotitlán Lagunas in Oaxaca recorded 81 mm of rain.

Local officials reported one person died after being swept away flood waters in Culiacán, Sinaloa on 17 August 2023. A vehicle carrying 5 people was swept away in Santa Rosalía in Mulegé Municipality in Baja California Sur on 19 August. The state government said one person died in the incident and four others escaped without harm.

In a statement of 19 August, Víctor Manuel Castro Cosío, Governor of Baja California Sur, said:

“I deeply regret the death of a person who, along with his family, was trapped trying to cross the Boleo stream in Santa Rosalia. I call on all citizens, especially to the north of our state: do not risk your lives trying to cross streams. Safety is above all else. Let’s avoid unnecessary hazards to our families and civil protection personnel.”

The state government has set up evacuation centres across numerous areas including Santa Rosalia, Guerro Negro, Mulegé, Vizcaino and San Ignacio.

“We will continue to provide support to those at risk, working alongside rescue teams and emergency services. We will face this adversity with unity and determination to keep our community safe,” the Governor said.

Hurricane Hilary a Category 1 Hurricane

Previously marked as a Category 4 hurricane, the State Civil Protection Council in Baja California Sur reported on 20 August 2023 that Hilary had weakened and was now Category 1 on the Saffir-Simpson scale. The storm was located 280 km south of Punta Eugenia in the municipality of Mulegé, Baja California Sur, with maximum sustained winds of 150 km/h. Waves of 5 to 7 metres were expected along the Pacific Coast.

The storm was moving north-northwest at 30 km/h, Civil Protection said. Hilary was expected to make landfall in Baja California Sur on 20 August, impacting areas of Punta Eugenia and Cedros Island. Hilary was then expected to move northwards and affect areas of San Quintín municipality in Baja California and on to California in the USA.

Track of Hurricane Hilary, Mexico and USA, August 2023. Image. NHC

State of Emergency in California, USA

On 19 August California Governor Gavin Newsom proclaimed a state of emergency for much of Southern California to support Hurricane Hilary response and recovery efforts as the state continues mobilizing and coordinating resources ahead of the storm’s forecasted impacts.

The National Hurricane Center said the storm is expected to bring “catastrophic and life-threatening flooding” to Baja California and the Southwestern U.S., including Southern California. Much of the impacts of the storm, including heavy rainfall and high winds, are expected to last until at least 21 August.

“California has thousands of people on the ground working hand-in-hand with federal and local personnel to support communities in Hurricane Hilary’s path with resources, equipment and expertise. We’re mobilizing all of government as we prepare and respond to this unprecedented storm,” the governor said.

According to NOAA NWS Weather Prediction Center, there is a high risk of flash flooding in areas of southern California. The risk extends into areas Arizona, Nevada, Utah and Oregon, the center said.

Flash flood Risk in western USA brought by potential heavy rainfall from Hurricane Hilary, August 2023. Image: NOAA NWS Weather Prediction Center