Western European Standard Time (WET)
UTC offset: +00:00 (standard), +01:00 during summer as WEST/BST/IST
IANA identifiers: Europe/London, Europe/Lisbon, Europe/Dublin, Atlantic/Canary
Abbreviations: WET (standard), WEST/BST/IST (summer)
Population covered: approximately 80 million across all observing territories
DST observed: Yes
Western European Time is UTC itself. Not offset from it, not ahead or behind, just zero. That makes it both the simplest time zone on earth to understand and, paradoxically, one of the most confusing to talk about, because it goes by so many names. The British call their standard time GMT. The Irish call their summer time IST (Irish Standard Time) and technically consider winter the "daylight saving" period. The Portuguese call it WET. The Canary Islands observe it even though the rest of Spain runs on CET. Everyone's on the same clock, but the branding varies wildly.
What WET Actually Covers
The countries and territories on Western European Time during winter:
- United Kingdom (England, Scotland, Wales, Northern Ireland)
- Ireland
- Portugal (mainland and Madeira, but not the Azores at UTC-01:00)
- Canary Islands (Spain)
- Iceland (UTC+00:00 year-round, no DST)
- Faroe Islands (Denmark)
- Several West African countries share the same offset but under different zone names (GMT, WAT in some contexts)
During summer, all of these except Iceland shift forward one hour. Iceland stays at UTC+00:00 permanently because it sits so far north that summer daylight lasts nearly 24 hours anyway, making DST pointless.
The GMT Connection
Greenwich Mean Time and Western European Time are functionally identical during winter. GMT was the original world reference time from 1884 until 1972, when Coordinated Universal Time (UTC) replaced it as the official global standard. The difference between GMT and UTC is negligible for civil purposes (they differ only in technical measurement methods related to the earth's slightly irregular rotation).
The Royal Observatory at Greenwich, where the Prime Meridian passes through the courtyard, remains the symbolic reference point. Tourists still stand on the brass line. But the actual atomic clocks that define UTC sit in laboratories in Paris (at the Bureau International des Poids et Mesures) and elsewhere.
In everyday use, "GMT" persists as a cultural label in the UK and among people worldwide who use it loosely to mean "the base time zone." Software systems should use UTC or the IANA identifiers rather than GMT, since GMT can be ambiguous (some systems treat it as a fixed offset, others as a zone that transitions to BST).
Portugal's CET Detour
Portugal tried Central European Time once. From 1992 to 1996, the country moved its clocks forward to align with Spain and France at UTC+01:00 (CET) in winter and UTC+02:00 (CEST) in summer. The motivation was European integration, specifically making business hours overlap more cleanly with Brussels, Frankfurt, and Madrid.
The experiment was unpopular. Portuguese winters already have short days at 38 to 42 degrees north latitude. Pushing the clock forward an hour meant dark mornings well past 8:30 a.m. in Lisbon during December. School children walked to class in full darkness. Public dissatisfaction was strong enough that Portugal reverted to WET/WEST in 1996 and has stayed there since.
The Canary Islands, which are Spanish territory at roughly the same longitude as western Morocco, use WET rather than the CET observed in mainland Spain. The islands sit between 13 and 18 degrees west longitude, making UTC+00:00 a better solar fit than UTC+01:00. Travelers flying from Madrid to Tenerife lose an hour on the clock despite flying south-southwest.
DST Schedule
Western European Summer Time begins on the last Sunday in March at 1:00 a.m. UTC (clocks jump from 1:00 to 2:00 a.m. local time). It ends on the last Sunday in October at 1:00 a.m. UTC (clocks fall from 2:00 to 1:00 a.m.).
The UK calls this British Summer Time (BST). Ireland calls it Irish Standard Time (IST), which is technically the non-DST name under Irish law, with winter time being the "anomaly." This legal inversion is a curiosity of Irish legislation but has no practical effect. The clocks move at the same time as everyone else.
The European Union proposed ending mandatory DST changes in 2019. The proposal stalled in the Council of the European Union and remains unresolved. If it ever passes, each member state would choose whether to stay on permanent summer or permanent winter time. Portugal and the Canary Islands would need to decide whether to stick with UTC+00:00 or shift to UTC+01:00 permanently. Ireland would face the same choice. The UK, no longer in the EU post-Brexit, would make its own decision independently.
Major Cities
London has about 9 million people in the city and 14 million in the broader metro area. It's one of the world's top three financial centers (alongside New York and, depending on who's measuring, Hong Kong or Singapore). The London Stock Exchange operates from 8:00 a.m. to 4:30 p.m. local time. The city's position at UTC+00:00/+01:00 gives it natural overlap with both Asian markets (which close in the London morning) and American markets (which open in the London afternoon).
Lisbon has about 2.9 million in the metro area and is Portugal's capital and primary economic center. Tourism, technology, and services drive the economy. Lisbon's startup scene has grown substantially since the Web Summit conference relocated there in 2016.
Dublin has about 1.4 million in the metro area and punches well above its weight as a European technology and pharmaceutical hub. Apple, Google, Meta, and many other multinationals use Dublin as their European headquarters, drawn partly by corporate tax rates and partly by the English-speaking workforce.
Edinburgh has about 540,000 people and is Scotland's capital. It's a financial services center (Royal Bank of Scotland, Standard Life Aberdeen) and hosts the world's largest arts festival (Edinburgh Festival Fringe) every August.
Business Overlap Advantage
The UTC+00:00 position gives Western Europe a unique scheduling advantage. During a standard London business day:
- At 8:00 a.m. London, it's 4:00 p.m. in Singapore and Hong Kong (end of Asian business day)
- At 2:30 p.m. London, it's 9:30 a.m. in New York (US market open)
- At 4:30 p.m. London, it's 11:30 a.m. in New York (full US overlap)
This positioning is a major reason London became a global financial center. No other major city gets meaningful overlap with both Asia and North America in the same business day. Frankfurt and Paris at UTC+01:00 are almost as good, but London's extra hour of Asian overlap tips the balance.
Neighboring Zones
| Zone | Offset | Difference from WET |
|---|---|---|
| Central European Time | UTC+01:00 | 1 hour ahead |
| Eastern European Time | UTC+02:00 | 2 hours ahead |
| Azores Time | UTC-01:00 | 1 hour behind |
| Iceland (permanent) | UTC+00:00 | Same, no DST |
| West Africa Time | UTC+01:00 | 1 hour ahead (no DST in most countries) |
The France/Spain/Portugal boundary is interesting. France and Spain use CET at UTC+01:00 despite their western regions being geographically within the WET band. This is a legacy of the German occupation during World War II, when France was moved to Berlin time and never changed back. Spain followed Franco's decision to align with Hitler's Germany in 1940 and also never reverted. Both countries operate with a clock that's roughly an hour ahead of their solar time, which contributes to their famously late dinner schedules.
Technical Identifiers
- Europe/London (canonical for the UK)
- Europe/Dublin (Ireland, with unusual legal DST inversion)
- Europe/Lisbon (Portugal mainland and Madeira)
- Atlantic/Canary (Canary Islands)
- Atlantic/Faroe (Faroe Islands)
- Atlantic/Reykjavik (Iceland, no DST)
The military/aviation designation for UTC+00:00 is Z ("Zulu"), the universal reference time.
Quick Reference
| Attribute | Value |
|---|---|
| UTC offset (standard) | +00:00 |
| UTC offset (summer) | +01:00 (WEST/BST/IST) |
| DST observed | Yes (except Iceland) |
| DST start | Last Sunday in March, 1:00 a.m. UTC |
| DST end | Last Sunday in October, 1:00 a.m. UTC |
| IANA zone (UK) | Europe/London |
| IANA zone (Portugal) | Europe/Lisbon |
| IANA zone (Ireland) | Europe/Dublin |
| Largest city | London (~14M metro) |
| Financial center | London |
| Notable quirk | Ireland legally considers summer time "standard" and winter the shift |