Temperatures are expected to exceed 40 degrees Celsius (104 degrees Fahrenheit) for the next three days in the northwestern border state of Sonora, with highs reaching 47 C in municipalities in the northwest and central region, according to Mexico’s National Meteorological Service (SMN).
The dangerous heat wave, which has lasted more than six weeks, has already caused 22 deaths and sickened 350 as of Tuesday morning, reports the Sonora state Health Ministry.
Temperaturas máximas registradas la tarde de ayer en estaciones de #Sonora
El valor mas alto que se presentó fue de 46.9°C en El Pinacate.
Fuentes: @ConaguaOCSonora, @CESAVE_Sonora. pic.twitter.com/XPq10IkZJH— Gilberto Lagarda Vas (@gilbertolagarda) August 18, 2026
The cities of San Luis Río Colorado, Caborca and Hermosillo could experience highs of between 43 C and 47 C. In the state capital of Hermosillo, the relative humidity is around 45%, while the ultraviolet radiation index is in the “extreme” category, ranging from 8 to 11.
The SMN is also monitoring summer monsoon conditions, with isolated storms reported in the mountainous regions of central and southern Sonora.
The State Civil Protection Coordination announced that monsoons will continue to bring rainfall across much of Sonora on Tuesday but will not cause temperatures to drop. Residents can expect moderate to heavy rain, lightning and gusty winds.
Construction and agricultural workers have been warned to take precautions, and employers are urged to schedule breaks during the workday to allow workers to hydrate and reduce their exposure during peak sun hours.
Health authorities are encouraging the public to stay hydrated, wear light-colored, lightweight clothing with long sleeves and use a hat or umbrella to protect themselves from the sun. People should avoid being outdoors during the hottest hours of the day, with older adults and children at greatest risk.
The main signs associated with heatstroke (golpe de calor) include severe headache, dizziness, confusion, nausea, very hot skin and loss of consciousness. Health authorities have advised the public to seek immediate medical attention by calling 911 if these severe symptoms occur.
With reports from La Jornada and El Sol de México
