Michigan · 182 m elevation

Barometric Pressure in Detroit, MI

• 30.03Average pressure (inHg, sea level)
• 239.3Swing days a year · 8th of 50
• 139.0Big-swing days a year (≥10 hPa)
• 140.2Significant 24h drop days a year

Overview

Detroit averages 30.03 inHg (1016.9 hPa) with 239.3 significant pressure swing days a year — 8th most volatile of 50 US cities. Seasonal data and records.

Detroit sits at 30.03 inHg (1016.9 hPa) on average at sea-level correction, with a median of 30.02 inHg (1016.7 hPa). Ninety percent of hours fall between 29.66 and 30.41 inHg (1004.5 and 1029.9 hPa). Those are unremarkable numbers for the northern United States. What sets Detroit apart is how often it moves between them, and how hard it can fall when a deep low tracks across the lower Great Lakes.

Across 2015–2024, Detroit logged 239.3 significant swing days per year — days with a 24-hour pressure change of at least 0.18 inHg (6 hPa) — ranking 8th of 50 US cities and running 1.32 times the national median of 180.7. Big-swing days of 0.30 inHg (10 hPa) or more came 139 times a year, 7th nationally and 1.61 times the median of 86.1. The city's steepest 24-hour fall on record, 1.40 inHg (47.5 hPa), ranks 3rd among all 50 cities, just behind Boston's 1.52 inHg (51.5 hPa) and New York's 1.41 inHg (47.6 hPa). That is coastal-storm territory produced 500 miles inland.

The overall spread is more moderate than the swing counts suggest: standard deviation is 0.23 inHg (7.66 hPa), ranking 11th. Detroit's signature is frequent, sharp transitions rather than an unusually wide range of readings. Chicago — same lake basin, nearly the same elevation — records 233.7 swing days, essentially a twin; Miami records 19.8, meaning Detroit sees 12.1 times as many swing days and 43 times as many big-swing days. Elevation also matters for what you read at home. Detroit sits at 182 meters, and mean station pressure is 29.38 inHg (994.9 hPa) against the sea-level-corrected mean of 30.03 inHg (1016.9 hPa). An uncorrected barometer will read roughly 0.65 inHg (22 hPa) low compared with broadcast or app values. Set the offset once and the trends line up.

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, Detroit is a demanding city in winter and a genuinely quiet one in summer. Averaged over the year it produces 239.3 significant swing days and 140.2 drop days — conditions many pressure-sensitive people report as triggers. Those totals are front-loaded into the cold season: about 17 drop days in February against fewer than 5 in July.

A typical Detroit day is calm. The median absolute 24-hour change is just 0.13 inHg (4.3 hPa), and 90% of 6-hour changes fall inside roughly ±0.14 inHg (−4.6 to +4.7 hPa). The volatility is episodic, concentrated in fast-moving systems: the 95th-percentile 24-hour move is 0.48 inHg (16.2 hPa), and the sharpest recorded 6-hour fall reached 0.50 inHg (17.1 hPa). Fronts here tend to arrive as a distinct event rather than a slow grind, which makes the pattern easier to anticipate from a forecast map than in cities with more constant low-grade churn.

Comparatively, Detroit ranks 8th of 50 for swing frequency and 7th for big swings, behind Denver's 281.6 swing days and effectively tied with Chicago's 233.7. It records 5.2 times as many swing days as Los Angeles and 12.1 times as many as Miami. If cold-season pressure changes are something you notice, November through March is when Detroit is most active; July and August are among the steadiest stretches any northern US city offers. Pressure swings are associated with symptoms some people report — not something anyone can predict — but the seasonal shape here is unusually clear.

Seasonal patterns

Detroit's pressure year has a hard seasonal spine. January averages 26.9 swing days, December 26.8, March 26.4, and February 26.1. July and August each average 9.5 — roughly a third as many. Monthly standard deviation follows the same curve: 0.29 inHg (9.71 hPa) in January and February, down to 0.13 inHg (4.26 hPa) in July and August. Drop days — significant 24-hour falls — peak in February at 16.8 and bottom out in July at 4.7.

The driver is storm track. From late fall through early spring, the polar jet sits over the lower Great Lakes, steering Alberta Clippers and deepening Colorado and Ohio Valley lows across the region. In summer the jet retreats north and the area settles under weak, flat ridging, which is why July readings drift rather than swing. Monthly mean pressure barely changes across the year — 30.09 inHg (1019.1 hPa) in January and November, 29.93 inHg (1013.6 hPa) in June — so the seasonal story is entirely about variability, not average level.

The extremes cluster where you would expect. The all-time low of 28.86 inHg (977.4 hPa) came at 9 p.m. on January 9, 2024 — the same hour that closed the record 24-hour fall of 1.40 inHg (47.5 hPa). The next four largest drops: 1.18 inHg (40.1 hPa) ending January 18, 2020; 1.10 inHg (37.3 hPa) on February 24, 2019; 0.96 inHg (32.5 hPa) on February 19, 2016; and 0.93 inHg (31.4 hPa) on November 15, 2020. All five occurred between November and February. The record high, 30.92 inHg (1047.0 hPa), was set under a strong Arctic high on the morning of February 9, 2019 — a 2.06 inHg (69.6 hPa) span between the decade's extremes.

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

• Cleveland, OH
• Columbus, OH
• Chicago, IL
• Indianapolis, IN
• Milwaukee, WI
• Louisville, KY

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