Watch, warning or advisory? Making sense of SoCal heat wave terms

It’s hot out there, and it’s only going to get hotter.

National Weather Service forecasters issued a slew of alerts this week as a heat wave settles into Southern California with even hotter weather right around the corner.

A heat advisory is in effect until Tuesday for much of the region, with triple-digit temperatures expected in some places. Then, from Tuesday through Thursday, July 16, L.A. County and its neighbors to the north are under a more severe extreme heat watch.

An extreme weather warning is already in place for the Coachella Valley, where highs are expected to approach 115 degrees on Friday.

Southern Californians are no strangers to hot weather in the summer, but heat waves are getting hotter, longer and more frequent as the climate changes.

And the words forecasters use to describe these weather events has changed too. The NWS rolled out new heat alert language last year after the previous summer broke records for the hottest in U.S. history.

So, what exactly triggers these heat alerts? And what should you do about them? Here’s a guide:

Heat Advisory: Advisories are issued when temperatures are expected to be hot enough to cause discomfort and potentially lead to heat-related illnesses, especially for more vulnerable populations like young children and the elderly. During a heat advisory, consider staying in a cool place and limiting outside activity, especially during the day. For those who spend time outside, be sure to drink plenty of water and take breaks in the shade.

Extreme Heat Watch: Watches are essentially forecasts for upcoming periods of extreme heat. Forecasters say heat watches often cover wide areas and will be revised into more focused warnings and advisories as conditions become clearer over time. Watches are a good time to prepare for extreme heat by, for example, locating a nearby cooling centers if you don’t have access to air conditioning.

Extreme Heat Warning: Warnings are issued when heat levels are or will likely become extremely dangerous. Under extreme heat warnings, it's a good idea to avoid strenuous outdoor activity, stay hydrated and help loved ones and pets stay cool.

Not one-size-fits-all

Forecasters say it is important to keep Southern California’s diverse geography in mind when thinking about what these alerts mean.

L.A. County, for example, covers beaches, valleys, mountains and deserts. Some areas have tree cover, while others are mostly concrete and asphalt. Temperatures can vary a lot between those landscapes. It might be 80 degrees near the coast when it’s 100 degrees in the desert.

Not everywhere under a heat advisory, watch or warning will necessarily see the highest temperatures in the forecast either. But it is likely that some places within the alert area will.

Heat is also experienced differently from community to community. For someone accustomed to living in the desert, 100-degree heat may feel different than it would for someone who lives near the beach.

National Weather Service forecasters often consult with local emergency management, fire and public health authorities about the needs of their particular residents when deciding where and when to issue alerts.