Arizona · 758 m elevation

Barometric Pressure in Tucson, AZ

• 29.92Average pressure (inHg, sea level)
• 66.6Swing days a year · 46th of 50
• 13.2Big-swing days a year (≥10 hPa)
• 29.4Significant 24h drop days a year

Overview

Tucson averages 29.92 inHg (1013.2 hPa) and just 66.6 significant pressure swing days a year — 46th of 50 US cities. Monthly patterns and records.

Tucson's barometer is one of the quietest in the country. Over the 2015–2024 record, mean sea-level pressure averaged 29.92 inHg (1013.2 hPa), with a median of 29.91 inHg (1012.8 hPa) and a standard deviation of only 0.14 inHg (4.61 hPa) — 46th of 50 major US cities on variability. The middle 90% of hours fall between 29.71 inHg (1006.2 hPa) and 30.16 inHg (1021.4 hPa), a narrow band by national standards.

Day-to-day movement is small. The typical 24-hour change is just 0.05 inHg (1.8 hPa), and only the top 5% of days exceed 0.20 inHg (6.7 hPa). Tucson logs 66.6 significant swing days per year — days with a 24-hour change of at least 0.18 inHg (6 hPa) — against a national median of 180.7. The median US city, in other words, sees about 2.7 times as many. Big-swing days of 0.30 inHg (10 hPa) or more come along 13.2 times a year versus a national median of 86.1, a 6.5-fold gap. Denver, the most volatile city in the set, records 4.2 times Tucson's swing days and 12.9 times its big-swing days. Only Los Angeles, Tampa, San Diego and Miami are calmer overall.

Tucson is also calmer than its regional peers. Las Vegas runs 2.0 times its swing-day count, El Paso 2.1 times, and Albuquerque 2.7 times. Even Phoenix, 425 meters lower, edges it slightly at 1.14 times the swing days. One practical note: at 758 meters elevation, Tucson's actual station pressure averages 27.42 inHg (928.7 hPa), about 2.50 inHg (84.5 hPa) below the sea-level-adjusted figures quoted in forecasts. An uncorrected home barometer will sit near 27.4 inHg permanently. Set the altitude correction, or simply expect that constant offset.

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, Tucson has one of the least active barometers in the country — but the calendar matters more here than almost anywhere. The city averages 29.4 drop days per year (a 24-hour fall of 0.18 inHg / 6 hPa or more) and 13.2 big-swing days of 0.30 inHg (10 hPa) or more. Both figures rank 46th of 50. The median US city sees 86.1 big-swing days; Tucson sees 13.2.

The concentration is what separates Tucson from a genuinely uniform city. February brings 5.8 drop days, January 5.1, December 4.9 — while July averages 0.2 and June 0.3. A February week in Tucson carries a real chance of the kind of rapid fall many pressure-sensitive people report as a trigger; a July week almost none. June through September is the calmest stretch of the year on the barometer, monsoon thunderstorms notwithstanding.

Against other cities: Denver records 12.9 times Tucson's big-swing days, and Boston's pressure varies 1.83 times as much hour to hour. Within the Southwest, Las Vegas and El Paso roughly double the swing-day count and Albuquerque comes close to tripling it. Phoenix is a near-match, marginally more active at 1.34 times the big-swing days. Only four US cities in this set are calmer than Tucson, and Tucson still records 3.4 times as many swing days as Miami. If you keep a log tied to pressure, the useful takeaway here is when to watch — roughly November through March — rather than year-round.

Seasonal patterns

Nearly all of Tucson's pressure activity is packed into the cool season. Of 66.6 significant swing days a year, 48.2 — 72% — fall between November and March. February leads with 11.0, followed by January at 10.8 and December at 10.7. Hour-to-hour variability follows the same curve, with monthly standard deviation peaking in February at 0.13 inHg (4.45 hPa). These are the months when Pacific troughs and cutoff lows reach southern Arizona and actually move the synoptic pattern.

Summer is close to flat. June through September together account for just 5.4 swing days, or 8% of the year: July 1.1, August 1.3, June 1.4, September 1.6. August is the least variable month of all at 0.08 inHg (2.73 hPa). This is counterintuitive if you judge by the sky — the monsoon delivers Tucson's most dramatic weather — but monsoon storms are local convection under a persistent thermal low, and they barely register in mean-sea-level pressure. Monthly averages trace that thermal low clearly, sliding from 30.07 inHg (1018.3 hPa) in January to 29.79 inHg (1008.9 hPa) in June, a seasonal range of 0.28 inHg (9.4 hPa).

The extremes line up with the cool season. The record high of 30.50 inHg (1032.7 hPa) came on January 28, 2017. The five sharpest 24-hour falls on record: 0.49 inHg (16.5 hPa) ending January 7, 2024; 0.45 inHg (15.3 hPa) on January 22, 2023; 0.42 inHg (14.2 hPa) on March 31, 2017; 0.39 inHg (13.2 hPa) on December 16, 2017; and 0.37 inHg (12.4 hPa) on January 21, 2017 — every one in the December-to-March window save the late-March event. The record low, 29.44 inHg (997.1 hPa), is the outlier: it occurred on October 11, 2023. The fastest 6-hour drop was 0.32 inHg (10.9 hPa), and the largest 24-hour rise 0.64 inHg (21.8 hPa).

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

• Phoenix, AZ
• El Paso, TX
• Albuquerque, NM
• Las Vegas, NV
• San Diego, CA
• Los Angeles, CA

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