Summer has yet to begin officially, but the weather isn't waiting until the summer solstice early Wednesday to kick things into high gear. Dangerous temperatures are expected to scorch the Southwest, providing no relief for days.
Phoenix, Las Vegas and Death Valley in California could break all-time record high temperatures. Cities including Los Angeles, Reno and San Diego are not in record territory, but are all expected to be well above average and will certainly feel unusually hot.
The days will be sweltering and the nights will prove to be no relief as the overnight low temperatures remain in the 90s for most of the affected area.
CNN meteorologist and hot-weather enthusiast Pedram Javaheri said this heat wave could be one for the history books.
"When you look at Phoenix, a city where record temperatures have been kept since August of 1895, there have been over 45,000 calendar days. Only four have reached or exceeded 119 degrees Fahrenheit and Tuesday could be the fifth in 45,000 days of record-keeping," Javaheri said.
Tucson is likely to tie or break the number of consecutive days above 110 Fahrenheit, a milestone not reached since 1994.
Las Vegas also gets into the extreme heat game during the week and could gamble with its highest temperature ever observed, which was 117 degrees Fahrenheit back in 2013. It will be close, as the current forecast for Vegas is 116 Fahrenheit.
These values are potentially deadly if the proper precautions are not taken.
Heat -- the deadliest type of weather
Heat kills more people in the United States than any other type of weather.
But it's not just the heat, it's the humidity. The heat index, a measure that combines the air's temperature and moisture content, essentially indicates what it will feel like when you step outside. The compounding effects of increasing temperature and humidity can be exceptionally dangerous.
Given the high temperature and humidity values forecast for this heat wave, it is important to watch for heat index values to get a better idea of the potential danger that awaits outside.
The National Weather Service is providing updates in the regional offices that are being affected by this heat wave.
Under a heat dome
High pressure is partly to blame for the prolonged expectancy of this heat wave. Over the next several days, high pressure will dominate in the Southwest, creating what is known as a heat dome.
Sinking air, associated with an area of high pressure, essentially traps the heat near the surface. When heat is trapped, health officials become concerned for not only heat exhaustion, but air quality as well.
"These [heat wave] conditions, coupled with what we call an atmospheric inversion, essentially trap pollution near the surface instead of it going up higher," said Patrick Chandler, a senior specialist for the South Coast AQMD (Air Quality Management District).
He explained that this process will trap the pollutants closer to people and will last for several days. Also worrying Chandler is the fact that this danger will extend over a broader area than usual.
"If the pollution layer is trapped low to people, then there's a higher instance for respiratory issues or other lung diseases," Chandler says.
"So that's why we are asking people to limit their outdoor activities [such as] running and playing outside when we have such unhealthy air quality."
How to beat the heat
With a busy Father's Day weekend on tap and likely to include outdoor activities such as barbecues and sporting events, it is important to know the dangers that extreme heat creates.
If you can't avoid being outside and staying close to air conditioning, here's some ways to beat the heat:
Don't forget to check on neighbors, friends, and family, especially the young or elderly who are at more risk of heath damage from excessive heat
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