Louisiana · 10 m elevation

Barometric Pressure in New Orleans, LA

• 30.04Average pressure (inHg, sea level)
• 80.8Swing days a year · 41st of 50
• 26.1Big-swing days a year (≥10 hPa)
• 39.8Significant 24h drop days a year

Overview

New Orleans sees 80.8 significant pressure swing days a year (#41 of 50 cities), yet its record low hit 29.11 inHg (985.7 hPa) on Aug 29, 2021.

New Orleans runs one of the flattest barometers in the country. Over the ten years from 2015 through 2024, sea-level pressure averaged 30.04 inHg (1017.4 hPa), with a standard deviation of just 0.15 inHg (5.01 hPa) — the 42nd-widest spread among the 50 cities tracked, against a national median of 0.20 inHg (6.87 hPa). Ninety percent of hours fall between 29.82 inHg (1009.9 hPa) and 30.32 inHg (1026.6 hPa), and the median reading, 30.03 inHg (1016.9 hPa), sits almost exactly on the mean. The typical 24-hour change is 0.05 inHg (1.8 hPa) — a barometer that mostly sits still.

The city is 10 meters above sea level, so there is essentially no elevation correction to worry about. Mean station pressure is 30.01 inHg (1016.2 hPa) versus 30.04 inHg (1017.4 hPa) at sea level — a gap of 0.04 inHg (1.2 hPa). An uncorrected home barometer in New Orleans reads what the airport reports, within the width of the needle.

By volume of activity, New Orleans ranks #41 of 50 for significant swing days, with 80.8 per year against a national median of 180.7 — Denver logs 281.6, about 3.5 times as many. But the ranking flips slightly when you look at severity: New Orleans places #39 for big-swing days at 26.1 per year, ahead of cities that see more total swings. Sacramento has 85.3 swing days but only 23.0 big ones; San Francisco records 80.6 swing days — statistically identical to New Orleans — but just 20.2 big-swing days, about 78% of the New Orleans figure. When pressure here does move, it tends to move hard.

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, New Orleans is a low-frequency city with a concentrated risk window. It averages 80.8 days a year with a 24-hour change of at least 0.18 inHg (6 hPa), and 39.8 of those are falls. That is well under half the national median of 180.7 swing days, and under a third of what Denver sees at 281.6. Compared with the calmest cities, though, it is not quiet: Miami records 19.8 swing days a year, so New Orleans has about 4.1 times as many, and 26.1 big-swing days of at least 0.30 inHg (10 hPa) against Miami's 3.2 — more than eight times as many. Houston, the nearest large Gulf peer, logs 107.3 swing days, about a third more than New Orleans, but its worst single-day fall in the decade was 0.63 inHg (21.4 hPa) versus 0.83 inHg (28 hPa) here.

The calendar matters more here than in almost any other city on this list. December through March is when nearly three-quarters of the movement happens — January averages 9.5 days with a significant pressure fall, February 7.1, December 6.6. Those months deliver conditions many pressure-sensitive people report as triggers, at a rate of roughly two per week in January. June through September, by contrast, averages well under one swing day per month; July and August average 0.2 drop days each, which is close to nothing.

The caveat is that the summer quiet is not uniform. The single largest pressure fall of the decade occurred on August 29, 2021, in a month that otherwise averages 0.3 swing days a year, and three more of the five sharpest drops fell in September and October. A tropical system near the coast can produce in a few hours the kind of change the barometer here would not otherwise show all season. For anyone tracking their own patterns, the practical shape of the New Orleans year is a busy but moderate winter, a nearly flat summer, and a small number of outlier days in late summer and autumn that are steeper than anything winter produces.

Seasonal patterns

The seasonal split is about as sharp as it gets. Of 80.8 significant swing days per year, 57.4 — 71% — fall in December through March. January alone averages 17.8 swing days and 9.5 drop days, with a monthly standard deviation of 0.19 inHg (6.38 hPa). Winter also carries the highest mean pressure: 30.15 inHg (1021 hPa) in January and 30.13 inHg (1020.2 hPa) in December, as cold-season fronts and the high-pressure air behind them sweep across the northern Gulf coast every few days.

Summer is the opposite regime. July averages 0.4 swing days, August 0.3, September 0.9, June 1.0 — the entire June-through-September block totals 2.6 swing days, and July and August each average 0.2 drop days. July's monthly standard deviation is 0.07 inHg (2.52 hPa). Mean pressure bottoms out at 29.97 inHg (1014.8 hPa) in June and September. Under the summer subtropical high, the barometer here does little beyond its daily tidal rise and fall.

The exception is what makes the record book. The lowest reading of the decade, 29.11 inHg (985.7 hPa), came at 7 p.m. on August 29, 2021 — the same day as the largest 24-hour fall on record here, 0.83 inHg (28 hPa), ending at 8 p.m. Four of the five sharpest 24-hour drops land in the tropical season: 0.69 inHg (23.2 hPa) on October 28, 2020; 0.58 inHg (19.5 hPa) on September 12, 2024; and 0.48 inHg (16.4 hPa) on October 26, 2019. The winter counterexample is 0.59 inHg (19.9 hPa) on January 9, 2024. The fastest six-hour fall was 0.52 inHg (17.6 hPa). At the other end, the decade's highest pressure, 30.77 inHg (1041.9 hPa), was recorded on the morning of January 8, 2017.

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

• Houston, TX
• Memphis, TN
• Atlanta, GA
• Dallas, TX
• Austin, TX
• Fort Worth, TX

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