When Can I Be Outside?

Hour-by-hour windows for outdoor time in St. George's desert heat, read on the National Weather Service scale.

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About these tools

Town Tools builds free, public tools for St. George and towns around the world. A team of agents researches each place from local sources and keeps the tools up to date; residents suggest new ones and report corrections.

Day

Best windows

Peak feels-like

Peak air

Tuesday, October 13

all day

56°F

40 · Good

Wednesday, October 14

all day

62°F

37 · Good

How this page decides

Heat uses the National Weather Service’s heat-index categories, applied to the modelled feels-like temperature: Caution 80°F–90°F, Extreme Caution 90°F–103°F, Danger 103°F–124°F, Extreme Danger 125°F and up.

Air uses the US EPA air quality index: Good 0–50, Moderate 51–100, Unhealthy for Sensitive Groups 101–150, Unhealthy 151–200, Very Unhealthy 201–300, Hazardous above that. The number here is that same EPA index, computed by Open-Meteo from the Copernicus CAMS model.

Each hour takes the harder of the two constraints, and the strip says which one. A “best window” means hours where the feels-like temperature stays below 80°F (below the NWS Caution band) and the air is no worse than Moderate — the EPA’s general-population activity cautions start at 101. No thresholds on this page are ours.

Reading it for your plans

The cool hours

The bearable hours in a Mojave-edge summer are right after dawn and after the sun drops. Locals clock trail runs, dog walks, golf and pickleball to the morning for a reason — by midday the pavement and red rock radiate heat long after the air temperature peaks.

Working and training outdoors

Construction crews, landscapers, and the city's heavy running and triathlon scene all face the same clock. This page shows when the heat eases, so the hardest efforts and outdoor shifts can be set for the least punishing parts of the day, with water before you feel thirsty.

Kids and older neighbors

About a fifth of St. George is over 65 and almost a quarter is under 18 — the two groups heat hits hardest. On extreme-heat days, check on older neighbors who live alone, and never leave children or pets in a parked car, which heats up far faster than the outdoor reading.

Worth knowing

Mojave Desert heat at 2,800 feet

St. George sits on the edge of the Mojave Desert in a hot-desert (BWh) climate: 100°F-plus summers, about 8 inches of rain a year, and roughly 255 sunny days. The dry air means shade and nightfall bring real relief, but daytime sun on sand, sandstone, and lava rock pushes surface heat well past the air temperature.

Source: NWS Salt Lake City, checked June 24, 2026

Who feels the heat first

Heat illness builds before it shows. The CDC notes infants and young children, people over 65, those with heart, lung, or kidney conditions, and anyone working or exercising outdoors are most at risk. Drink water on a schedule rather than by thirst, rest in shade or air conditioning, and learn the signs of heat exhaustion and heat stroke.

Source: CDC — Extreme Heat, checked June 24, 2026