Heat in the latter half of the month proved to be fatal across the Phoenix metropolitan area. Temperatures rose into the upper 90s to around 100 as high pressure aloft built into the Southwest.
Every event with a place to put it; 3 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PSR wrote it up.
Heat in the latter half of the month proved to be fatal across the Phoenix metropolitan area. Temperatures rose into the upper 90s to around 100 as high pressure aloft built into the Southwest. According to the Maricopa County Department of Public Health, there were 2 heat-caused fatalities and 3 heat-related fatalities in Maricopa County May 20-25. As reported to Phoenix, the data are aggregrated and represent monthly values for several combined communities. Unfortunately, specifics such as age, gender, location of fatality, and circumstances cannot be obtained.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Phoenix, AZ wrote its last area forecast discussion before the first event at May 19, 10:57 PM MST, 1 hour 3 minutes earlier.
Area Forecast Discussion National Weather Service Phoenix AZ 1057 PM MST Sat May 19 2018 .UPDATE...Updated Aviation Discussion. && .SYNOPSIS... A seasonably warm and dry weather pattern will prevail through the middle of the week along with clear to mostly clear skies. Expect daytime temperatures near seasonal norms through Wednesday with breezy conditions anticipated early in the workweek. Beginning late in the week and early next weekend a noticeable warming trend will likely usher in high temperatures back into the low 100s by Friday with chances of an even warmer weekend. && .DISCUSSION... The latest upper air analysis shows our area sitting between two low pressure systems, the one that has since lifted northeast out of our area and a second system approaching the west coast. For today, dry zonal flow will keep our skies mostly clear and temperatures warming to near normal values. The models are still in good agreement showing the approaching system deepening across the west coast by late Sunday and Monday. Unfortunately, our area will remain dry under mostly southwesterly flow aloft. The surface pressure gradient will tighten which will aid in the development of some strong breezes for Sunday and Monday afternoons with the strongest winds over southeast California, particularly in western Imperial County, and in the higher terrain north and east of Phoenix. The primary concern will be elevated fire weather conditions considering the dry and breezy conditions. Otherwise, we may see some high level clouds and near normal temperatures. This system will do its best yo-yo impersonation and quickly lift back to the north towards the Great Basin by Tuesday. However, model guidance is in disagreement heading further into the workweek. At least some minor ridging should occur midweek allowing temperatures to increase by the weekend with even just modest H5 height increases. However, the European model wants to bring a another low into our area towards the end of the week which would bring cooler temperatures and breezy conditions. Conversely, the GFS continues with fairly strong ridging which, climatologically, is an easier pill to swallow and a more likely outcome. We will have to see how the atmosphere shapes up over the next few days. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL, and Southeast California/Southwest Arizona including KIPL and KBLH: There are no significant aviation weather concerns through tomorrow morning as winds follow typical diurnal headings and remain fairly light outside of a few westerly gusts at KBLH tonight. Winds tomorrow afternoon and evening will be stronger than today as the surface pressure gradient strengthens ahead of an upper-level disturbance approaching from the west. S-SW wind gusts up to 20-25 knots will be possible at KIPL and KBLH, but W-SW gusts should remain below 15 knots at the Phoenix sites. && .FIRE WEATHER... Tuesday through Saturday: Dry and seasonable temperatures will continue. A dry low pressure system will cause some breezy conditions Tuesday afternoon for parts of the Tonto NF which may be of some concern given the very dry conditions. Minimum relative humidity values will stay in the 7-15 percent range with overnight recoveries into the 20-30 percent range. The area will undergo a warming trend approaching 100 degrees but there is uncertainty for the forecast heading towards next weekend. However, the most likely scenario is for very warm and dry conditions to continue with moderate afternoon breezes. && .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && DISCUSSION...Deemer AVIATION...Hopper FIRE WEATHER...Deemer
The national radar mosaic for the moment the first event began.
3 heat. Local standard time, as filed.
Temperatures rose into the upper 90s to around 100 , resulting in abnormally hot conditions. According to the Maricopa County Department of Public Health, there were 3 heat fatalities (1 direct and 2 indirect).
Temperatures rose into the upper 90s to around 100 , resulting in unusually hot conditions. According to the Maricopa County Department of Public Health, there was 1 direct heat fatality.
Temperatures rose into the upper 90s to around 100 , resulting in unusually hot conditions. According to the Maricopa County Department of Public Health, there was 1 indirect heat fatality.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Heat, Central Phoenix | 2018-05-20 | Unknown | Direct | ||
| Heat, Central Phoenix | 2018-05-23 | Unknown | Indirect | ||
| Heat, Central Phoenix | 2018-05-25 | Unknown | Indirect | ||
| Heat, East Valley | 2018-05-20 | Unknown | Direct | ||
| Heat, North Phoenix/Glendale | 2018-05-22 | Unknown | Indirect |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2018Every state in 2018This day in weather historyWarnings in Arizona, May 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 854805, 854806, 854807.