Colorado · 1615 m elevation

Barometric Pressure in Denver, CO

• 29.97Average pressure (inHg, sea level)
• 281.6Swing days a year · 1st of 50
• 169.8Big-swing days a year (≥10 hPa)
• 177.5Significant 24h drop days a year

Overview

Denver records 281.6 significant pressure swing days a year — the most of 50 US cities and 1.56x the national median. Seasonal patterns and records.

Denver's barometer moves more often than any other city in this 50-city set. Between 2015 and 2024 it logged 281.6 significant swing days per year — days when the 24-hour change reached at least 0.18 inHg (6 hPa) — against a national median of 180.7. That is roughly 1.56 times the median and works out to about 77% of all days. Big-swing days, where the change reaches 0.30 inHg (10 hPa), came 169.8 times a year, nearly twice the national median of 86.1 and second only to Colorado Springs at 171.6.

The typical numbers themselves are unremarkable. Sea-level-reduced pressure averaged 29.97 inHg (1014.8 hPa) with a median of 29.96 inHg (1014.5 hPa), and 90% of hours fell between 29.58 inHg (1001.7 hPa) and 30.38 inHg (1028.9 hPa). What sets Denver apart is the cadence, not the ceiling. The median absolute 24-hour change is 0.14 inHg (4.9 hPa) — just under the swing threshold, meaning an ordinary Denver day is nearly a significant swing day. The standard deviation of 0.24 inHg (8.17 hPa) ranks 5th of 50.

Elevation matters for anyone reading a barometer at home. At 1615 m, Denver's mean station pressure is 24.74 inHg (837.7 hPa) — about 177 hPa below the sea-level-reduced figure. A unit displaying raw station pressure will sit near 24.7 inHg; one set to altimeter or sea-level correction will read near 30.0. Every comparative statistic on this page uses the sea-level reduction, which is the standard for cross-city comparison and which, at this altitude, amplifies temperature-driven variation somewhat. That is part of why Denver and Colorado Springs sit at the top of the national list together — 281.6 and 279.6 swing days respectively. This is a Front Range signature, not a Denver quirk.

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 pressure changes against their symptoms, Denver is the most active barometric environment in this set. Significant swings arrive on 281.6 days a year, and drop days — significant 24-hour falls, the direction many pressure-sensitive people report as the more noticeable one — come 177.5 times a year. In the top 5% of 24-hour changes, the move reaches 0.50 inHg (17 hPa). Six-hour changes reach 0.21 inHg (7 hPa) at the 95th percentile, with a record six-hour fall of 0.59 inHg (20.1 hPa). These are conditions many pressure-sensitive people report as triggers, and in Denver they occur on most days of the year.

The seasonal contrast is clear. November carries the most drop days at 19.3, with March at 18.4 and February at 18.2. July is the quietest at 7.4 drop days and August is close behind at 8.3, so a mid-winter or early-spring month delivers more than twice the drop days of a midsummer one. July and August are the only sustained quiet stretch in the Denver year; September swing days climb back to 18.1.

Comparatively, Denver runs 14.2 times Miami's 19.8 annual swing days and about 53 times its 3.2 big-swing days; big-swing days here are 22.6 times Los Angeles's 7.5. Against Boston, third nationally at 257.6 swing days, Denver adds about 24 more per year — though Boston's worst single drop, 51.5 hPa, exceeds anything Denver recorded. Salt Lake City has slightly higher overall variability (0.26 inHg / 8.64 hPa standard deviation, first nationally) yet only 221.3 swing days, so Denver crosses the threshold about 1.27 times as often on a marginally smaller base. The practical upshot for anyone keeping a symptom log here: the swings are close to daily and follow a clear seasonal rhythm, so patterns show up in the calendar rather than in isolated storm events.

Seasonal patterns

The turbulent stretch runs from late autumn through spring. March is the busiest month at 28.5 swing days, followed by November at 28.3, December at 27.8, April at 27.7 and February at 26.8. Month-to-month variability tracks the same shape: February is the most scattered at 0.29 inHg (9.82 hPa) standard deviation, with December at 0.28 inHg (9.37 hPa) close behind. The driver is the cold-season jet crossing the Rockies and the lee cyclogenesis it triggers east of the Front Range, reinforced by the alternation between downslope chinook flow and upslope easterly surges.

Summer is the genuine break. August averages 14.8 swing days and July 15.3 — roughly half the March figure — and July's standard deviation drops to 0.13 inHg (4.34 hPa), less than half February's. Monsoon-season convection is a daily affair but barely shifts the daily mean. Monthly average pressure runs from 30.08 inHg (1018.6 hPa) in January down to 29.86 inHg (1011.2 hPa) in June, an annual range of only about 7 hPa — small next to the day-to-day churn.

The emblematic event is a 48-hour sequence in January 2015. Pressure peaked at the period record of 31.16 inHg (1055.2 hPa) at 10:00 on January 7, 2015, then collapsed: the largest 24-hour fall in the record, 1.16 inHg (39.2 hPa), ended at 09:00 on January 8. The record low, 29.05 inHg (983.6 hPa), came on April 12, 2022. Other steep 24-hour drops all fall in the cold season: 0.97 inHg (32.9 hPa) ending February 16, 2021; 0.96 inHg (32.5 hPa) on March 2, 2015; 0.92 inHg (31.1 hPa) on January 7, 2022; and 0.88 inHg (29.8 hPa) on December 15, 2016. Rises can be equally abrupt — the largest 24-hour gain was 1.18 inHg (40.1 hPa). Notably, Denver's single worst drop ranks only 14th of 50 nationally; frequency, not severity, is what defines this city.

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

• Colorado Springs, CO
• Albuquerque, NM
• Salt Lake City, UT
• Wichita, KS
• Omaha, NE
• Oklahoma City, OK

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