USA and Mexico – Evacuations and Rescues After Flooding Rain From Storm Rosa

The remnants of Hurricane Rosa brought heavy rain and flooding to parts of Mexico and Arizona USA from 01 October 2018.

Hurricane Rosa formed in the East Pacific and reached Category 4 status at its peak. Rosa then weakened and was downgraded to a tropical storm and later a tropical depression.


In Mexico, heavy rainfall was reported in the northern states of Sonora and Baja California, where authorities declared an emergency in the municipalities of Ensenada and Mexicali.

Severe flooding was reported in San Felipe in Baja California after around 100 mm of rain fell on 01 October. Some areas of Sonora recorded between 70 and 100 mm of rain in 2 days to 01 October. One person reportedly died in flood waters from an overflowing river in Caborca, Sonora state.

Expected track of Storm Rosa through northern Mexico and South West USA. Image: NHC


In the USA, Phoenix, Arizona, saw its wettest October day ever, with 2.36 inches / 59.94 mm of rain falling on 02 October, 2018. According to NWS Phoenix, Storm Rosa brought more rain in 3 days (3.38 inches / 85.85 mm, 30 September to 02 October) than Phoenix saw for the monsoon this year (2.56 inches / 65 mm, 15 June to 29 September).

NWS Phoenix said the heavy rain quickly overwhelmed urban drainage systems, causing numerous road closures. Flooded roads and accidents caused severe traffic problems, and several people had to be rescued from trapped vehicles. Many creeks and washes in the area were flowing at high levels.

Flooding was reported in around 40 locations in Pinal and Maricopa counties, which includes areas of Phoenix, Mesa, Scottsdale and Glendale. Some schools were closed on Tuesday, 02 October, due to the heavy rain and flooding.

Meanwhile further south, evacuations were advised out for communities near Menegers Lake on the Tohono O’odham Nation Reservation after NWS Tucson warned that a dam failure was imminent. Affected families were advised to move to the village of Ali Chuk for safety.

Flooded roads were reported in Tucson and also the city of Yuma on the U.S.-Mexico border.

California, Nevada and Utah

Flash flood watches were also in effect in for parts of California, Nevada and Utah. Utah Governor Gary Herbert declared a state of emergency due to potential flooding in the state.

Record rainfall in Phoenix, AZ, after Storm Rosa, October 2018. Image: NWS Phoenix

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Flood Summary

Last updated: October 4, 2018
Hurricane Rosa, Mexico and USA, October 2018
October 1, 2018
Flash flood
Extreme rainfall
The remnants of Hurricane Rosa brought heavy rain and flooding to parts of Mexico and Arizona USA from 01 October 2018. One person reportedly died in Caborca, Sonora. Heavy rain caused surface flooding in parts of Phoenix and Tucson, AZ, and increased levels of the Menegers Lake on the Tohono O'odham Nation Reservation, where a potential dam failure prompted evacuation advisories.


A - Caborca, Sonora (Mexico)
B - San Felipe (Mexico)
C - Ensenada (Mexico)
D - Mexicali (Mexico)
E - Phoenix (United States)
F - Tucson (United States)
G - Tohono O'odham (United States)
H - Yuma (United States)


Rainfall level
59.94 mm in 24 hours
Phoenix, AZ, USA - October 2 to October 2, 2018
According to NWS
Rainfall level
100 mm in 24 hours
San Felipe, Baja California, Meixco - October 1 to October 1, 2018
According to local observers


1 person
Caborca, Sonora, Mexico - October 1 to October 1, 2018