Nevada · 609 m elevation

Barometric Pressure in Las Vegas, NV

• 29.91Average pressure (inHg, sea level)
• 132.4Swing days a year · 34th of 50
• 49.0Big-swing days a year (≥10 hPa)
• 66.9Significant 24h drop days a year

Overview

Las Vegas averages 29.91 inHg (1012.7 hPa) and 132.4 significant swing days a year — 18.6 in December but just 1.7 in August. Monthly data and records.

Las Vegas sits at a mean sea-level pressure of 29.91 inHg (1012.7 hPa) across 2015–2024, with a median of 29.88 inHg (1011.7 hPa). That is the second-lowest average of the 50 cities tracked here, behind only Phoenix — a signature of the semi-permanent thermal low that dominates the Desert Southwest for much of the year. Ninety percent of hours fall between 29.62 and 30.27 inHg (1003.1 and 1025.2 hPa).

Elevation matters more here than the sea-level numbers suggest. The station sits at 609 m, and mean surface pressure is 27.88 inHg (944 hPa) — about 2.03 inHg (69 hPa) below the sea-level-adjusted value. A home barometer reporting raw station pressure will read near 27.88 inHg on an average day, not 29.91. That is not an instrument fault; it is the missing 2,000 feet of atmosphere. Most consumer barometers allow an altitude correction, and without it your readings will never match the numbers in a forecast discussion.

Nationally, Las Vegas is a low-frequency city with above-average tails. It records 132.4 significant swing days per year — days with a 24-hour change of at least 0.18 inHg (6 hPa) — ranking #34 of 50 against a national median of 180.7. Big-swing days of 0.30 inHg (10 hPa) or more come 49 times a year, ranking #36 against a median of 86.1. But the standard deviation of 0.20 inHg (6.87 hPa) ranks #25 and matches the national median exactly. Quiet days are common here; the distribution around them is not narrow. On a typical day pressure moves only 0.07 inHg (2.5 hPa) in 24 hours, while the 95th-percentile day moves 0.30 inHg (10.1 hPa).

Migraine & pressure-sensitivity outlook

• Low — under 6 hPa (0.18 inHg)
• Elevated — 6 to 10 hPa
• High — 10 hPa (0.30 inHg) or more
• Dashed outline = forecast (after today)

Association only. This calendar shows days when pressure changed — or is forecast to change — sharply over 24 hours, conditions associated with pressure sensitivity in some people. It is not a prediction of symptoms, not a diagnosis, and not medical advice. The 30 days of history are there so you can compare the days you actually felt something against what the barometer did. Talk to a clinician about headache or migraine management.

For people who track barometric pressure, Las Vegas is a favorable but uneven city. It sees 66.9 drop days per year — significant 24-hour falls of 0.18 inHg (6 hPa) or more — which averages out to about one every five and a half days. Big-swing days of 0.30 inHg (10 hPa) or more arrive 49 times a year, well under the national median of 86.1. Against Denver, the most volatile city in this set, Las Vegas has under a third the big-swing days (49 vs. 169.8). Los Angeles, four hours away, has 6.5 times fewer (7.5 per year).

Those events are concentrated rather than spread evenly. January alone accounts for 10.2 drop days, December 9.7, and February 9.1, while July and August together account for about one. The November-through-April window is where Las Vegas delivers the conditions many pressure-sensitive people report as triggers; late summer is about as quiet as the continental United States gets. The individual events can be substantial: the 0.81 inHg (27.5 hPa) fall ending February 21, 2023 is nearly double the deepest single drop Phoenix has recorded over the same decade, 0.44 inHg (14.9 hPa).

Among regional peers, Las Vegas lands in the middle. It has 1.75 times Phoenix's swing days (132.4 vs. 75.8) and 2.8 times its big-swing days, so the assumption that all desert cities are barometrically flat does not hold. El Paso is the closest statistical match nationally — 139.7 swing days and 49.6 big-swing days, nearly identical annual counts — though Las Vegas carries a wider overall spread (6.87 vs. 6.03 hPa) and a deeper worst case (0.81 inHg vs. 0.58 inHg / 19.6 hPa). Anyone weighing Las Vegas for pressure stability should read it as a summer of near-total calm paired with a cool season that is genuinely active, not as uniform quiet year-round.

Seasonal patterns

Las Vegas runs two different pressure climates in one calendar year. December logs 18.6 swing days, January 18.0, and February 17.0. August logs 1.7 — roughly one-eleventh of December's count. July is barely better at 2.1, and June comes in at 3.9. The same split shows in month-to-month variability: February and January standard deviations of 6.89 and 6.53 hPa fall to 3.16 in July and 3.22 in August. From late June through mid-September, the barometer here is one of the flattest in the country.

The driver is straightforward. From November through April, the Pacific storm track and inside-slider troughs reach the Mojave, and each passing system drags the barometer down and back up. In summer, the thermal low over the Desert Southwest holds pressure low and level — monthly means bottom out at 29.73 inHg (1006.6 hPa) in June and 29.78 inHg (1008.4 hPa) in July, against 30.12 inHg (1019.9 hPa) in January and 30.11 inHg (1019.5 hPa) in December. Even monsoon thunderstorms, locally dramatic as they are, barely register in the synoptic-scale pressure record.

The extremes cluster in the cool season. The record low of 29.14 inHg (986.8 hPa) came at 10 PM on February 21, 2023, and that same timestamp closes out the largest 24-hour fall in the record: 0.81 inHg (27.5 hPa). The next four largest drops were 0.74 inHg (24.9 hPa) ending February 2, 2020; 0.64 inHg (21.8 hPa) on March 30, 2017; 0.60 inHg (20.2 hPa) on October 11, 2021; and 0.57 inHg (19.2 hPa) on January 21, 2019. The record high, 30.71 inHg (1039.8 hPa), was set on the morning of January 28, 2017. The fastest six-hour fall on record is 0.42 inHg (14.1 hPa), and rises are as sharp as falls — the largest 24-hour rise, 0.81 inHg (27.6 hPa), essentially mirrors the largest drop.

Month by month

Swing days: 24-hour change of at least 6 hPa (0.18 inHg). Drop days: 24-hour fall of at least 6 hPa. Averages per year, 2015–2024.

Records and extremes

Sharpest 24-hour drops, 2015–2024

Nearby cities

• Los Angeles, CA
• Phoenix, AZ
• Fresno, CA
• San Diego, CA
• Salt Lake City, UT
• Tucson, AZ

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