The National Weather Service has issued an Excessive Heat Watch for the Santa Clarita Valley from Friday, July 21 in the morning until Saturday evening July 22. Dangerously hot conditions with temperatures up to 110 possible for interior valleys, mountains and deserts and up to 105 possible for coastal valleys.

The extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities.

Heat watches are issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours. A Watch is used when the risk of a heat wave has increased but its occurrence and timing is still uncertain.

Avoid outdoor exercise and exertion during the heat of the day, keep hydrated and do not leave pets or children unattended in vehicles. Check on older adults during the Excessive Heat Watch.

The South Coast Air Quality Management District has extended an air quality alert in inland areas of the South Coast Air Basin including the Santa Clarita Valley until 8 p.m. on Saturday, July 22.

Elevated levels of ozone, the predominant summertime pollutant, are likely to result in poor air quality in the afternoon and early-evening hours. Ozone air pollution can cause respiratory health problems, including trouble breathing, asthma attacks and lung damage. Children, older adults and people with asthma or COPD may be more sensitive to the health effects of ozone.

Air quality can change depending on time of day and weather conditions. Increased emissions of chemicals and faster ozone formation rates due to heat, along with low winds and stagnant weather can cause unusually high and persistent levels of ozone pollution.

To help minimize ozone air pollution levels:

— Limit the use of gasoline powered lawn and garden equipment until evening hours.

— Conserve electricity and set your air conditioner at a higher temperature.

— Try to delay trips to the gas station and the use of household chemicals until the evening.