Georgia · 327 m elevation

Barometric Pressure in Atlanta, GA

• 30.08Average pressure (inHg, sea level)
• 115.6Swing days a year · 37th of 50
• 44.5Big-swing days a year (≥10 hPa)
• 62.0Significant 24h drop days a year

Overview

Atlanta averages 30.08 inHg (1018.5 hPa) with just 115.6 significant swing days a year, #37 of 50 US cities for pressure volatility. 2015-2024 data.

Atlanta runs high and steady. Across 87,672 hourly observations from 2015 through 2024, mean sea-level pressure averaged 30.08 inHg (1018.5 hPa) — the highest average of any of the 50 US cities in this comparison. The median reading was 30.07 inHg (1018.2 hPa), and the middle 90% of all hours fell between 29.82 inHg (1009.9 hPa) and 30.37 inHg (1028.4 hPa). That is a narrow band. The standard deviation of 0.17 inHg (5.61 hPa) ranks #37 of 50, well below the national median of 6.87 hPa.

Day to day, the barometer barely moves. The typical 24-hour change in Atlanta is 0.07 inHg (2.3 hPa), and only one day in twenty sees a change of 0.28 inHg (9.6 hPa) or more. The city logs 115.6 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. Big-swing days of 0.30 inHg (10 hPa) or more come 44.5 times a year, roughly half the national median of 86.1. Denver, the most volatile city in the set, records 281.6 swing days, about 2.4 times Atlanta's count, and 169.8 big-swing days, about 3.8 times as many. Within the Southeast, Atlanta is calmer than Charlotte (158.8 swing days, 1.37 times Atlanta's), Nashville (151.1) and Raleigh (175.9).

One local detail matters for anyone reading a home instrument. Atlanta sits at 327 meters, so actual station pressure averages 28.94 inHg (980.1 hPa) — about 1.13 inHg (38.4 hPa) below the sea-level-corrected value in public forecasts. An uncalibrated barometer here will read near 28.9, not 30.1. That offset is close to constant; it shifts the scale but not the day-to-day movement you are tracking.

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, Atlanta is a comparatively quiet city with a genuine off-season. The 115.6 days a year with a 24-hour change of 0.18 inHg (6 hPa) or more — the size of change many pressure-sensitive people report as a trigger — is about two-thirds of the national median of 180.7. The 44.5 big-swing days of 0.30 inHg (10 hPa) or more come in at roughly half the median. Drop days, meaning significant 24-hour falls specifically, average 62 per year. Against Colorado Springs, which logs 171.6 big-swing days, Atlanta sees about a quarter as many. Against Miami, the calmest city in the set at 19.8 swing days, Atlanta sees about 5.8 times more.

The seasonal concentration is the useful part. Roughly 63% of Atlanta's swing days fall in December through March, and January alone contributes 20.3 swing days and 11.7 drop days. July is effectively blank: 0.4 swing days and no drop days at all across ten years of records, with August close behind at 0.8 swing days and 0.3 drop days. That kind of predictable quiet stretch does not exist in Denver or Boston, where turbulence is spread across the calendar. If you keep a symptom log, the entries worth comparing against the barometer will cluster from December through March.

The caveat is that a calm average does not cap the extremes. Atlanta's largest 24-hour fall of 0.91 inHg (30.9 hPa) ranks #25 of 50 nationally, and the September 27, 2024 event fell 0.77 inHg (26.2 hPa) in a day while bottoming out at the decade's record low of 29.03 inHg (982.9 hPa). Tropical systems and deep winter lows produce a handful of days each decade as sharp as anything in a far more volatile city. Pressure changes are associated with symptoms some people report; they are one variable among many, and individual responses vary widely.

Seasonal patterns

Atlanta's year splits cleanly in two, and winter behaves like a different city than summer. January averages 30.16 inHg (1021.3 hPa) with a monthly standard deviation of 0.21 inHg (7.24 hPa), and December is nearly identical at 30.16 inHg (1021.4 hPa). July averages 30.03 inHg (1016.9 hPa) with a standard deviation of 0.09 inHg (2.98 hPa) — less than half the winter figure.

The swing counts show the same split more starkly. January produces 20.3 significant swing days, February 18.3, December 17.3 and March 16.8. December through March accounts for 72.7 of the year's 115.6 swing days, about 63% of the annual total in a third of the calendar. Then it stops. July averages 0.4 swing days and zero drop days across the full decade; August averages 0.8 swing days. The driver is straightforward: the winter storm track and its cold-front passages reach north Georgia regularly from late fall into early spring, while in summer the Bermuda high settles over the Southeast and pressure flattens. Summer weather in Atlanta arrives as convection rather than as marching pressure systems.

The extremes tell the other half of the story. Despite ranking #37 for overall volatility, Atlanta's sharpest 24-hour drop of 0.91 inHg (30.9 hPa) ranks #25 of 50 — squarely mid-pack, and larger than the worst drops recorded in Fort Worth (22.0 hPa) or Dallas (21.5 hPa), both of which see more swing days per year than Atlanta does. That drop ended at 11:00 on January 9, 2024. The decade's other big movers split between winter lows and tropical systems: 0.77 inHg (26.2 hPa) ending 06:00 on September 27, 2024 — the same hour as the record low of 29.03 inHg (982.9 hPa); 0.73 inHg (24.7 hPa) on September 11, 2017; 0.69 inHg (23.2 hPa) on January 23, 2019; and 0.61 inHg (20.5 hPa) on December 14, 2019. The record high, 30.79 inHg (1042.6 hPa), came on January 8, 2017. The largest 24-hour rise was 0.82 inHg (27.8 hPa), and the fastest six-hour fall was 0.49 inHg (16.7 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

• Nashville, TN
• Charlotte, NC
• Jacksonville, FL
• Louisville, KY
• Memphis, TN
• Raleigh, NC

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