Las Vegas weather and climate guide

7-day forecast for Las Vegas

This Afternoon in Las Vegas, NV brings chance showers and thunderstorms, with a high near 96°F and a low around 79°F. Across the 7-day outlook, highs average 100°F and lows average 81°F, ranging from 77°F to 107°F. 2 of the 7 days carry at least a 30% chance of precipitation, so keep rain gear handy.

Current conditions

Observed at Las Vegas, North Las Vegas Airport (KVGT) at 5:35 PM PDT.

Dry heat, and what that actually means

July averages 105 °F by day. The all-time record is 120 °F, reached in July 2024. But relative humidity in summer often sits between 10 and 20%, which changes the physiology substantially.

In dry air, sweat evaporates almost immediately and carries heat away efficiently. The heat index at 105 °F with 15% humidity is actually slightly below the air temperature. That is why 105 in Las Vegas is genuinely more tolerable than 95 in Houston, and why the standard NWS heat index table is less useful in the Mojave than in the Southeast.

The trap is that efficient evaporation is invisible. You can lose well over a liter of water an hour walking the Strip in July without ever feeling sweaty, because it evaporates as fast as it appears. Dehydration and heat exhaustion arrive without the usual warning signs. Alcohol, which is not exactly scarce here, accelerates it.

Surface temperatures are the other underrated danger. Asphalt and concrete in direct July sun exceed 160 °F, hot enough for contact burns in seconds and hot enough to injure dogs' paws in under a minute. Red Rock Canyon and Valley of Fire have both had heat fatalities among hikers who started too late in the day with too little water.

Flash flooding is the deadliest hazard

This surprises people in a city that gets four inches of rain a year, but flash flooding kills more people in southern Nevada than heat does in some years, and the mechanism is straightforward.

Desert soil is baked hard and hydrophobic, so it absorbs almost nothing. The valley is surrounded by steep mountains that funnel runoff downward into a network of normally dry washes. The urban area has added enormous impervious surface. When a monsoon thunderstorm drops an inch in thirty minutes over the Spring Mountains, that water arrives in the valley as a fast-moving wall within an hour.

The critical detail is that the storm does not have to be over you. Water can come down a wash under a completely clear blue sky, from rain falling fifteen miles away in the mountains. This is why NWS Flash Flood Warnings here cover areas that are not raining, and why hikers in slot canyons anywhere in the Southwest need to know the forecast for the entire upstream drainage rather than for their location.

Clark County has built an extensive detention basin and channel system in response, and it works, but streets and parking garages still flood in strong events. Most deaths involve vehicles. Six inches of moving water can float a small car, and two feet will carry away most vehicles.

Monsoon season

From mid-June through September, the regional circulation shifts and draws moisture north from the Gulf of California. Las Vegas is on the northwestern edge of the North American Monsoon, so it gets less reliable monsoon precipitation than Phoenix or Tucson — some years bring several soaking events and some bring almost nothing.

When storms do form, they behave the same way as elsewhere in the Southwest: highly localized, violent, and often producing strong outflow winds well ahead of the rain. Dust storms occur here too, though less frequently than in Arizona.

One monsoon feature specific to the desert is the dry microburst. Rain falls from a high cloud base into very dry air and evaporates before reaching the ground, which cools that air and accelerates it downward. The result is a violent downdraft producing 60 to 70 mph surface winds with little or no rain — hazardous for aviation at Harry Reid International and for anything temporary and outdoors.

Winter nights are colder than visitors expect

December averages 58 °F by day and 39 °F at night, and the valley floor drops below freezing on a number of nights each winter. The diurnal range is the story: clear, dry desert air holds very little heat, so the ground radiates warmth away rapidly after sunset. A 30 to 35 °F swing between afternoon and pre-dawn is completely normal year-round.

Visitors who arrive in November expecting desert warmth and pack accordingly are consistently uncomfortable walking outdoors at 10 p.m. It is a legitimately cool climate at night for half the year.

The mountains are a different climate entirely. Mount Charleston, less than an hour from the Strip, rises to nearly 12,000 feet, gets several feet of snow annually and supports a small ski area. Being able to reach snow in forty minutes from a desert city is one of the genuinely unusual features of living here.

Drought and the Colorado River

This is the long-term weather story that matters most locally. Las Vegas draws roughly 90% of its water from Lake Mead, which is fed by the Colorado River, which is fed primarily by snowpack in the Rocky Mountains hundreds of miles away. The city's water supply depends on weather it does not experience.

Sustained drought across the Colorado Basin since 2000 dropped Lake Mead to record lows in 2022, exposing the original 1971 intake structure and prompting the first federally declared shortage on the river. Southern Nevada's response has been aggressive: a third intake tunnel drilled deep beneath the lake, near total recycling of indoor water back to the lake, and a ban on non-functional decorative turf. Per capita water use has fallen substantially even as population grew.

The practical relevance for a weather site is that the Sierra and Rocky Mountain snowpack reports in April tell you more about southern Nevada's year than any local rainfall total does.

Weather hazards to know about

• Extreme heat

  May through September

  Highs above 105 °F for weeks. Dry air masks fluid loss, so dehydration arrives without the usual warning signs.

• Flash flooding

  Mid-June through September, and winter storm events

  The deadliest hazard here. Water can arrive in a dry wash from rain falling miles away under a clear sky overhead.

• Microbursts and high wind

  Monsoon season and spring

  Dry microbursts generate 60 to 70 mph surface winds with little rain. Spring frontal winds also regularly exceed 50 mph.

• Extreme UV exposure

  Year-round, most intense April through September

  Low latitude, elevation, minimal cloud cover and reflective desert surfaces push the UV index to 11 or higher in summer.

• Cold desert nights

  October through April

  A 30 to 35 °F daily swing is normal, and valley freezes happen. Visitors consistently underpack for evenings.

What to wear and pack, by season

Spring (March to May)

Warm-weather clothing plus a real layer for evenings, and sun protection. Windy season, so something wind-resistant helps.

Summer (June to September)

Light, loose, ideally long-sleeved sun-protective fabric, a hat, sunglasses, and far more water than seems necessary. Indoor spaces run aggressively cold.

Fall (October to November)

The best season. Comfortable days, with a jacket needed after sunset.

Winter (December to February)

A medium jacket, plus warm layers if you plan to be outdoors at night. Snow gear only if you are heading up Mount Charleston.