California · 22 m elevation

Barometric Pressure in Sacramento, CA

• 29.98Average pressure (inHg, sea level)
• 85.3Swing days a year · 39th of 50
• 23.0Big-swing days a year (≥10 hPa)
• 40.6Significant 24h drop days a year

Overview

Sacramento averages 29.98 inHg (1015.3 hPa) with just 85.3 significant pressure swing days a year — and 81% of them fall between November and April.

Sacramento's barometer averages 29.98 inHg (1015.3 hPa) at sea-level reference, with a standard deviation of 0.16 inHg (5.47 hPa) across 87,672 hours of 2015–2024 data. Half of all hours sit within a narrow band near the median of 29.96 inHg (1014.6 hPa); the 5th and 95th percentiles are 29.75 inHg (1007.5 hPa) and 30.27 inHg (1025.0 hPa). Day to day, the typical 24-hour change is only 0.06 inHg (2.1 hPa) — small enough that most people would never notice it without an instrument.

At 22 meters of elevation, the altitude correction is minor. Station pressure averages 29.91 inHg (1012.7 hPa), about 0.08 inHg (2.6 hPa) below the sea-level-adjusted value. A home barometer left uncorrected in Sacramento will read only slightly under what the airport and forecast products report.

Nationally, Sacramento sits toward the quiet end. It records 85.3 significant swing days per year (24-hour change of at least 0.18 inHg / 6 hPa), ranking #39 of 50 cities and coming in at 47% of the national median of 180.7. Big-swing days of at least 0.30 inHg (10 hPa) run 23 per year, rank #40, roughly 3.7 times fewer than the national median of 86.1. Its variability ranks #40 as well. But the ranking that matters most is the outlier one: Sacramento's deepest 24-hour fall of 0.69 inHg (23.5 hPa) ranks #37, meaningfully higher than its everyday-volatility ranks. This is a city that stays quiet for months and then delivers a real drop.

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, Sacramento's profile is unusually front-loaded onto the calendar. There are 40.6 drop days per year — significant 24-hour falls — and they are concentrated: January averages 7.7 and December 7.1, while June and July each average 0.3. The 95th-percentile 24-hour move is 0.23 inHg (7.7 hPa), so even on an active day the swing is modest by national standards. From roughly May through October, the conditions many pressure-sensitive people report as triggers are close to absent.

Compared with the rest of the country, Sacramento is gentle. Denver, the most volatile city in the set, logs 281.6 swing days a year — 3.3 times Sacramento's total — and 169.8 big-swing days, 7.4 times Sacramento's 23. Against the national median, Sacramento sees fewer than half as many swing days. Within California the picture is more nuanced: it runs nearly even with San Francisco (80.6 swing days) but ahead of Fresno on both counts, with 1.18 times Fresno's swing days and 1.52 times its big-swing days, and 1.87 times as many swing days as Los Angeles.

The practical takeaway is timing rather than intensity. Roughly four out of five significant swings arrive in a six-month window from November through April, and the largest single events on record — including the 0.69 inHg (23.5 hPa) fall of February 17, 2017 — all occurred during storm season. If you keep a symptom log, the winter and early-spring months are where any correlation would show up here, and the deep summer stretch offers a long, unusually flat baseline for comparison.

Seasonal patterns

The seasonal split here is more extreme than in almost any other city on this list. Of Sacramento's 85.3 annual swing days, 69.1 — 81% — fall between November and April. June through September accounts for just 7.0, about 8%. August averages 0.8 swing days per year, meaning most Augusts pass without a single 0.18 inHg (6 hPa) move in 24 hours. July runs 1.0. Monthly variability follows the same curve: 6.23 hPa in January versus 2.49 hPa in July.

The cause is structural. In summer the Central Valley sits under the Pacific High with a thermal trough and the delta breeze setting the daily rhythm; no fronts reach Sacramento, and the barometer flattens. December and January each average 13.7 swing days, with February at 12.0 and March at 12.3, as Pacific frontal systems and atmospheric rivers track up the valley. Mean pressure tracks the same seasons — 30.12 inHg (1020.0 hPa) in December and January, sagging to 29.86 inHg (1011.2 hPa) in June.

The extremes cluster in winter, and the winter of 2017 owns the record book. The all-time high of 30.62 inHg (1036.9 hPa) came on January 28, 2017; the all-time low of 29.21 inHg (989.1 hPa) came just three weeks later on February 17, 2017 — a 1.41 inHg (47.8 hPa) spread within a single season. That same February 17 produced the sharpest 24-hour fall on record, 0.69 inHg (23.5 hPa) through 3 p.m., with the record low arriving five hours later. The next deepest drops: 0.60 inHg (20.2 hPa) ending February 4, 2024; 0.59 inHg (20.0 hPa) ending November 27, 2019; 0.54 inHg (18.4 hPa) ending March 21, 2023; and 0.53 inHg (18.0 hPa) ending January 20, 2017. The fastest 6-hour fall on record is 0.36 inHg (12.3 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

• San Francisco, CA
• San Jose, CA
• Fresno, CA
• Los Angeles, CA
• Las Vegas, NV
• San Diego, CA

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