Kentucky · 144 m elevation

Barometric Pressure in Louisville, KY

• 30.06Average pressure (inHg, sea level)
• 178.8Swing days a year · 26th of 50
• 91.8Big-swing days a year (≥10 hPa)
• 101.8Significant 24h drop days a year

Overview

Louisville averages 178.8 significant pressure-swing days a year (#26 of 50 cities), but its worst 24-hour drop, 1.16 inHg (39.2 hPa), matches Denver's.

Louisville's mean sea-level pressure over the 2015-2024 period is 30.06 inHg (1017.9 hPa), with a median of 30.04 inHg (1017.4 hPa). Most hours fall in a fairly tight band: the 5th percentile is 29.75 inHg (1007.5 hPa) and the 95th is 30.41 inHg (1029.8 hPa), with a standard deviation of 0.20 inHg (6.77 hPa). A typical 24-hour change is just 0.09 inHg (3.1 hPa) — small enough that most days pass without any barometric event worth noting.

The city sits at 144 meters, and that shows up on any barometer not corrected to sea level. Station pressure averages 29.55 inHg (1000.6 hPa), about 0.51 inHg (17.3 hPa) below the sea-level figure quoted in forecasts. If your home barometer reads near 29.55 inHg on an ordinary day, it is working correctly.

The national ranking undersells this city. Louisville's 178.8 significant swing days per year put it at #26 of 50, marginally below the national median of 180.7, and its standard deviation ranks #26. But big-swing days — 24-hour changes of 0.30 inHg (10 hPa) or more — run 91.8 per year, above the national median of 86.1 and good for #24. Its sharpest 24-hour fall ranks #15. The pattern is consistent: Louisville has an average number of active days and an above-average share of hard ones. Compare Albuquerque, which logs slightly more swing days (180.7) but only 75.5 big-swing days; Louisville produces 1.22 times as many heavy changes on fewer active days.

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.

Louisville produces 178.8 days a year with a 24-hour change of at least 0.18 inHg (6 hPa), and 101.8 of those are falls — conditions many pressure-sensitive people report as triggers. What distinguishes the city is the upper end: 91.8 days a year cross the 0.30 inHg (10 hPa) big-swing threshold, and the 95th-percentile 24-hour change is 0.39 inHg (13.3 hPa). Fewer active days than the Plains and Great Lakes cities, but a higher proportion of them are heavy.

The useful comparison is Denver, which ranks #1 nationally with 281.6 swing days — 1.57 times Louisville's — and 1.85 times its big-swing days. Yet Denver's worst 24-hour drop on record is 1.16 inHg (39.2 hPa), identical to Louisville's. Frequency and force are different things. Regionally, Louisville runs 1.18 times Nashville's swing days but 1.27 times its big-swing days, and 1.55 times Atlanta's swing days with 2.06 times the big swings. Against Miami, the calmest city in the set, Louisville has 9.0 times the swing days.

Plan around the calendar rather than a flat annual average. December through March carry 23.9 to 26.1 swing days each and 14.4 to 15.3 drop days, meaning roughly one significant fall every other day. July and August carry 1.2 and 1.3 drop days respectively for the entire month. If you track your own patterns against barometric readings, the winter half of the year is where the signal will be, and the summer half offers a long, genuinely quiet stretch.

Seasonal patterns

The year splits almost in half. January is the most turbulent month by a wide margin: 26.1 swing days, 15.3 of them drops, a monthly standard deviation of 0.27 inHg (9.01 hPa), and the year's highest mean at 30.15 inHg (1021.1 hPa). December (24.7 swing days), March (24.1), and February (23.9) follow closely. July is the quietest: 2.5 swing days, 1.2 drop days, and a standard deviation of 0.10 inHg (3.26 hPa). January delivers roughly 10.4 times July's swing-day count.

The driver is the cold-season storm track. From November through March, the Ohio Valley sits beneath a strong temperature gradient, and clipper systems and Gulf-moisture lows cross the region on sharp pressure gradients. In summer the gradient collapses; June's mean of 29.96 inHg (1014.5 hPa) and July's 29.99 inHg (1015.5 hPa) sit lower than winter's, but they sit there quietly, with convective storms producing changes too brief and too small to register as 24-hour swings.

The extremes cluster accordingly. All five of the sharpest 24-hour drops on record fall between January and March: 1.16 inHg (39.2 hPa) ending January 9, 2024; 0.94 inHg (31.8 hPa) ending March 3, 2023; 0.84 inHg (28.6 hPa) ending January 25, 2023; 0.84 inHg (28.3 hPa) ending February 24, 2016; and 0.82 inHg (27.7 hPa) ending January 18, 2020. The record low of 28.93 inHg (979.7 hPa) was set at the bottom of that March 3, 2023 plunge — the same timestamp ends both. The record high, 30.92 inHg (1047.1 hPa), came on February 9, 2019, under deep cold-season high pressure. The fastest six-hour fall on record is 0.55 inHg (18.7 hPa); the largest 24-hour rise is 1.08 inHg (36.6 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

• Indianapolis, IN
• Nashville, TN
• Columbus, OH
• St. Louis, MO
• Chicago, IL
• Cleveland, OH

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