Methodology and Sources | Time Zone Hell

Rules last verified Oct 21, 2026. This page explains how every time on the site is worked out and where each rule comes from.

How times are calculated

Every conversion is done through Coordinated Universal Time (UTC). We find the UTC moment for the time you enter, then work out the local time in each place for that exact moment and date.
For most places we use the rules in the IANA time zone database, the same rulebook used by phones, computers and calendars, as built into your browser.
For the places that changed in 2026 (BC, Alberta, the NWT, Manitoba and the areas that follow them), we apply the new fixed offsets ourselves from Nov 1, 2026. That way the answers are right even if your browser or device still has an older copy of the rulebook. Dates before Nov 1, 2026 use the old rules.
Daylight saving time in Canada and the US starts at 2:00 AM local time on the second Sunday in March and ends at 2:00 AM local time on the first Sunday in November.

How places are matched to time zones

Cities come from GeoNames (about 40,000 places, including every Canadian and US community over 1,000 people). Airports come from OurAirports.
Each place is assigned a time zone from its exact location using official time zone boundaries (timezone-boundary-builder, built from OpenStreetMap). This is how Cranbrook ends up on Alberta's time and Kenora on Manitoba's.
Local exceptions we handle by hand: Golden, BC (moved to BC time on Nov 1, 2026), Creston and BC's Peace River region (UTC−7 all year), Lloydminster, Atikokan, Blanc-Sablon and the Navajo Nation.

The rules we use, and where they come from

Where	Rule we use	Source
British Columbia	UTC−7 all year. Last clock change March 8, 2026; no fall-back on Nov 1, 2026. Southeastern BC (East Kootenay) follows Alberta; Golden moves to UTC−7.	BC Gov News: Adopting permanent daylight saving time (Mar 2, 2026) Province of BC: B.C.’s new time zone
Alberta	Alberta Time (ABT), UTC−6 all year, under Bill 31, the Red Tape Reduction Statutes Amendment Act, 2026. Clock-change sections proclaimed June 18, 2026; no fall-back on Nov 1, 2026.	CTV News: “Alberta Time” legislation tabled IANA time zone database 2026c (Alberta change)
Northwest Territories	Northwest Territories Time, UTC−6 all year. Regulations in force Aug 21, 2026; no fall-back on Nov 1, 2026.	Government of the NWT: Northwest Territories ends seasonal time change (Sept 23, 2026)
Manitoba	UTC−5 all year (daylight time kept permanently). Last clock change March 8, 2026; no fall-back on Nov 1, 2026.	Manitoba Legislature: Bill 223, The Official Time Amendment Act, 2025 The Weather Network: Manitoba adopts permanent daylight time
Northwestern Ontario (Kenora and nearby)	Stays on Central Daylight Time (UTC−5) all year to stay aligned with Manitoba, from Nov 1, 2026. Announced by Ontario on Oct 13, 2026.	City of Kenora: City welcomes Ontario’s decision (Oct 13, 2026)
Yukon	Yukon Standard Time, UTC−7 all year since 2020. No change in 2026.	Time in Yukon (overview)
United States	Still changes clocks (second Sunday in March, first Sunday in November), except Arizona and Hawaii. The Sunshine Protection Act (H.R. 139) passed the House on July 14, 2026; the Senate has not voted.	Congress.gov: H.R. 139, Sunshine Protection Act of 2025 House Energy & Commerce Committee: House passes legislation
Time zone database	IANA time zone database release 2026e (Sept 29, 2026), which includes the BC, Alberta, NWT and Manitoba changes.	IANA: Time Zone Database release 2026e

Where

Rule we use

Source

British Columbia

UTC−7 all year. Last clock change March 8, 2026; no fall-back on Nov 1, 2026. Southeastern BC (East Kootenay) follows Alberta; Golden moves to UTC−7.

BC Gov News: Adopting permanent daylight saving time (Mar 2, 2026)
Province of BC: B.C.’s new time zone

Alberta

Alberta Time (ABT), UTC−6 all year, under Bill 31, the Red Tape Reduction Statutes Amendment Act, 2026. Clock-change sections proclaimed June 18, 2026; no fall-back on Nov 1, 2026.

CTV News: “Alberta Time” legislation tabled
IANA time zone database 2026c (Alberta change)

Northwest Territories

Northwest Territories Time, UTC−6 all year. Regulations in force Aug 21, 2026; no fall-back on Nov 1, 2026.

Government of the NWT: Northwest Territories ends seasonal time change (Sept 23, 2026)

Manitoba

UTC−5 all year (daylight time kept permanently). Last clock change March 8, 2026; no fall-back on Nov 1, 2026.

Manitoba Legislature: Bill 223, The Official Time Amendment Act, 2025
The Weather Network: Manitoba adopts permanent daylight time

Northwestern Ontario (Kenora and nearby)

Stays on Central Daylight Time (UTC−5) all year to stay aligned with Manitoba, from Nov 1, 2026. Announced by Ontario on Oct 13, 2026.

City of Kenora: City welcomes Ontario’s decision (Oct 13, 2026)

Yukon

Yukon Standard Time, UTC−7 all year since 2020. No change in 2026.

Time in Yukon (overview)

United States

Still changes clocks (second Sunday in March, first Sunday in November), except Arizona and Hawaii. The Sunshine Protection Act (H.R. 139) passed the House on July 14, 2026; the Senate has not voted.

Congress.gov: H.R. 139, Sunshine Protection Act of 2025
House Energy & Commerce Committee: House passes legislation

Time zone database

IANA time zone database release 2026e (Sept 29, 2026), which includes the BC, Alberta, NWT and Manitoba changes.

IANA: Time Zone Database release 2026e

Known limits

Some small communities set their own time by local custom, and a few First Nations follow a different time from the surrounding area. We follow the official boundaries, so check locally if you're scheduling something there.
Northwestern Ontario communities other than Kenora are assumed to follow Manitoba as Ontario announced; the international time zone database makes the same assumption.
Time zone codes: Alberta calls its time ABT and BC calls its time PCT. Manitoba and the NWT haven't announced short codes, so we show CDT for Manitoba (Central Daylight Time kept all year, as Ontario describes it for Kenora) and CST for the NWT (the label in the international time zone database).
Rules for future years can change. We review the rules whenever a government announces a change and whenever a new time zone database release comes out.

Found something wrong? See corrections.