The National Weather Service has issued an excessive heat warning for the Santa Clarita Valley that is expected to continue until Thursday evening.

The warning, issued at 11 a.m. today, cautions residents that temperatures expected to reach 105 degrees can cause heat exhaustion in individuals, especially those engaging in strenuous outdoor activities.

The Occupational Safety and Health Administration recommends those who work outside take frequent rest breaks in shaded or air-conditioned areas.

Anyone observed overcome by heat should be moved to a cool area and emergency personnel summoned, the weather service warned.