Live · KPSM · reported 1 h 6 min ago
Barometric pressure in Portsmouth, New Hampshire today
29.61inHg
1002.8 hPa (mb)
- 3-hour change
- −0.01 inHg · −0.3 hPa
- 24-hour range
- 29.59 – 29.67 inHg
- Station (absolute) pressure
- 29.59 inHg
- Barometer dial reads
- Rain · slightly low
Last 7 days
7-day barometric pressure graph for Portsmouth
Over the last 7 days, barometric pressure in Portsmouth ranged from 29.59 inHg (today) to 30.48 inHg (Monday). The sharpest fall was 0.29 inHg within six hours, on Monday.
| Day · inHg | High | Low | Change |
|---|---|---|---|
| Today | 29.65 | 29.59 | 0.00 |
| Sat, Nov 7 | 29.80 | 29.62 | −0.18 |
| Fri, Nov 6 | 29.85 | 29.78 | −0.04 |
| Thu, Nov 5 | 30.11 | 29.82 | −0.10 |
| Wed, Nov 4 | 30.14 | 29.94 | −0.20 |
| Tue, Nov 3 | 30.23 | 30.15 | −0.04 |
| Mon, Nov 2 | 30.48 | 30.18 | −0.25 |
Altimeter setting from KPSM (METAR), one report per hour. “Change” is the first to the last report of that day; today is so far.
Portsmouth at a glance
How elevation shapes the reading in Portsmouth
Portsmouth is about 20 ft (6 m) above sea level. That is close to sea level, so the pressure you stand in and the sea-level figure in the forecast are nearly the same.
The reading above is the altimeter setting from Portsmouth Intl (KPSM), 5 km (3 mi) from the city center. It is the station’s measured pressure corrected to sea level, which is the number weather reports, apps and TV forecasts use, so you can compare Portsmouth with any other city.
Portsmouth elevation and what it means · Sea-level vs station pressure
| Elevation | 20 ft · 6 m |
|---|---|
| Weather station | Portsmouth Intl (KPSM) |
| Station elevation | 112 ft · 34 m |
| Standard air pressure at this elevation | 29.90 inHg · 1013 hPa |
| Air pressure vs sea level | 100% |
| Water boils at | 212.0 °F · 100.0 °C |
| Time zone | America/New York |
Reading the barometer
Is the pressure in Portsmouth high or low?
Today’s reading is slightly low. Weather pressure is quoted at sea level, so the same scale works for Portsmouth and everywhere else.
- Very low Stormy < 29.50
- Low Clouds, rain 29.50–29.80
- Normal Changeable 29.80–30.20
- High Fair 30.20–30.50
- Very high Dry, clear > 30.50
Frequently asked questions
What is the barometric pressure in Portsmouth today?
The live reading at the top of this page is the latest sea-level pressure reported by Portsmouth Intl (KPSM), 5 km (3 mi) from the city center. It updates about every 10 minutes; the graph shows the last 24 hours.
What is normal barometric pressure in Portsmouth?
Weather reports for Portsmouth use sea-level pressure, so “normal” is the same as anywhere: about 29.92 inHg (1013 hPa), with most days between 29.60 and 30.30 inHg (1002–1026 hPa). Readings above 30.20 inHg are high pressure; below 29.80 inHg is low pressure.
Why does a barometer in Portsmouth read lower than the forecast?
Portsmouth is close to sea level (about 20 ft), so absolute and sea-level pressure differ by only about 0.02 inHg (1 hPa). A larger gap usually means the barometer needs to be calibrated against the reading on this page.
Where can I see a 7-day barometric pressure graph for Portsmouth?
The graph on this page shows the last 7 days of hourly sea-level pressure from KPSM, with each day's high and low in the table below it. Its sharpest fall usually marks a front or storm passing through.
Is the pressure in Portsmouth rising or falling?
See the trend badge under the reading: it compares the latest report with the one three hours earlier. Falling pressure usually means clouds, wind or rain on the way; rising pressure means clearing and more settled weather.