Altimeter Setting — Weather Glossary
A pressure value adjusted to mean sea level used primarily in aviation to calibrate aircraft altimeters. It differs from simple station pressure because it includes standardised assumptions about the atmosphere. Although mainly an aviation term, it relates directly to how pressure is reported and compared between locations. A UK-focused definition with clear usage notes for day-to-day forecast reading.
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Altimeter Setting — Definition
A pressure value adjusted to mean sea level used primarily in aviation to calibrate aircraft altimeters. It differs from simple station pressure because it includes standardised assumptions about the atmosphere. Although mainly an aviation term, it relates directly to how pressure is reported and compared between locations.
Deep Dive: Key Points
A compact way to interpret Altimeter Setting is to ask three questions: what is driving it, where is it most relevant, and what changes when it appears in a forecast?
- Driver: pressure, airmass, stability or upper-level support.
- Location: exposed coasts/hills versus sheltered inland spots.
- Outcome: cloud/visibility changes, rainfall organisation, or wind shifts.
Why This Term Matters in the UK
Altimeter Setting is typically used as a forecasting reference, rather than a headline in its own right. In UK practice it helps explain the reasoning behind changes in cloud, wind or precipitation, particularly when Atlantic systems are shaping the pattern.
With the UK sitting on the edge of the North Atlantic storm track, small shifts in the wider setup can change local outcomes quickly. For that reason, this glossary keeps meanings consistent and focuses on practical interpretation.
We keep glossary definitions consistent across our UK pages to support clear comparisons between England, Scotland, Wales and Northern Ireland.
Where You’ll See It in Forecast Text
This term is often deployed in a ‘cause → effect’ structure: 'because Altimeter Setting applies, you can expect…' That keeps the wording concise without becoming vague.
- Typically appears once per section rather than repeated.
- Often paired with another concept (front, inversion, airmass).
- Used to make uncertainty explicit when it matters.
Practical Interpretation
If the term relates to a process (rather than a single condition), it often describes why the weather is changing rather than what the sky looks like at a specific moment.
- In changeable patterns, expect windows of better weather between bands.
- If winds fall light, local effects (fog/low cloud) become more likely.
- If mixing increases, gustiness and shower intensity can rise.
What This Term Does 'Not' Mean
- Do not treat this as a guarantee of rain, sun, or wind on its own.
- Small track shifts can change local outcomes without changing the overall pattern.
- A forecast term can be correct even if your exact location experiences a short-lived exception.
Related Concepts
The quickest way to deepen understanding is to follow the related links. They are selected to be conceptually adjacent, not just similar-sounding.
Return to the main glossary for quick browsing: Weather Glossary (A–Z).