The yellow alert, which indicates a risk score of 7 out of 16, is in effect from 9pm on Thursday, to 8am on Saturday.
The alert is likely to have minor impacts on health and social care services, with vulnerable people potentially needing more healthcare, and an increased risk to their lives.
Indoor environments might also become uncomfortably warm.
Guidance has been provided to help professionals respond to the alert, with specific action cards available for commissioners, health and social care providers, and others.
The Met Office may issue National Severe Weather Warnings at short notice, so residents are advised to stay updated.
People who are especially vulnerable to hot weather are advised to follow published safety guidelines.
The Heat-Health Alert Service is active from June 1 to September 30 each year, with the potential for extraordinary alerts outside this period if necessary.
