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Fixes various inconsistencies and outdated mappings in timezone data #585

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Fixes various inconsistencies and outdated mappings in timezone data #585

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054d9b1
Fixes various inconsistencies in timezone names and cities
niranjan-uma-shankar Jul 29, 2025
72948db
Update gmt offset
niranjan-uma-shankar Jul 29, 2025
91c6134
Reorder GMT offset
niranjan-uma-shankar Jul 30, 2025
b7b921d
Update former city name
niranjan-uma-shankar Jul 30, 2025
7c80eb3
Removes Tijuana from America/Los_Angeles and adds it back as a separa…
niranjan-uma-shankar Aug 12, 2025
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39 changes: 26 additions & 13 deletions packages/timezone-data/src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -13,12 +13,16 @@ const timezoneData: {name: string; label: string}[] = [
},
{
name: 'America/Tijuana',
label: '(GMT -8:00) Chihuahua, La Paz, Mazatlan'
label: '(GMT -8:00) Tijuana'
},
{
name: 'America/Los_Angeles',
label: '(GMT -8:00) Pacific Time (US & Canada); Tijuana'
label: '(GMT -8:00) Pacific Time (US & Canada)'
},
{
name: 'America/Mazatlan',
label: '(GMT -7:00) La Paz, Mazatlan'
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nit: it might make sense to put the city that matches the time zone first (especially since there's two different "La Paz" in this file), unless there's a reason for doing it this way i'm not aware of.

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Thanks for the suggestion. The timezone isn’t exposed to the user in the frontend, only the label is. The cities in the label follow alphabetical order, and putting Mazatlan in front would break this order. Was there a specific reason you think putting the city matching the timezone first would work better here?

},
{
name: 'America/Phoenix',
label: '(GMT -7:00) Arizona'
Expand All @@ -27,6 +31,10 @@ const timezoneData: {name: string; label: string}[] = [
name: 'America/Denver',
label: '(GMT -7:00) Mountain Time (US & Canada)'
},
{
name: 'America/Chihuahua',
label: '(GMT -6:00) Chihuahua'
},
{
name: 'America/Costa_Rica',
label: '(GMT -6:00) Central America'
Expand Down Expand Up @@ -57,7 +65,7 @@ const timezoneData: {name: string; label: string}[] = [
},
{
name: 'America/Caracas',
label: '(GMT -4:00) Caracas, La Paz'
label: '(GMT -4:00) Caracas, La Paz, Georgetown'
},
{
name: 'America/Halifax',
Expand All @@ -73,7 +81,7 @@ const timezoneData: {name: string; label: string}[] = [
},
{
name: 'America/Argentina/Buenos_Aires',
label: '(GMT -3:00) Buenos Aires, Brasilia, Georgetown'
label: '(GMT -3:00) Buenos Aires, Brasilia'
},
{
name: 'America/Noronha',
Expand Down Expand Up @@ -175,6 +183,10 @@ const timezoneData: {name: string; label: string}[] = [
name: 'Asia/Kabul',
label: '(GMT +4:30) Kabul'
},
{
name: 'Asia/Almaty',
label: '(GMT +5:00) Almaty, Astana'
},
{
name: 'Asia/Karachi',
label: '(GMT +5:00) Islamabad, Karachi, Tashkent'
Expand All @@ -185,39 +197,40 @@ const timezoneData: {name: string; label: string}[] = [
},
{
name: 'Asia/Kolkata',
label: '(GMT +5:30) Chennai, Calcutta, Mumbai, New Delhi'
label: '(GMT +5:30) Chennai, Kolkata, Mumbai, New Delhi'
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nit: i know this list was already existing, but same suggestion here about putting the city that matches the time zone first in the list (again, unless there's a reason for the order)

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Similar to my earlier comment, the cities here are in alphabetical order, so putting Kolkata first would break that.

},
{
name: 'Asia/Kathmandu',
label: '(GMT +5:45) Katmandu'
name: 'Asia/Colombo',
label: '(GMT +5:30) Colombo, Sri Jayawardenepura'
},
{
name: 'Asia/Almaty',
label: '(GMT +6:00) Almaty, Novosibirsk'
name: 'Asia/Kathmandu',
label: '(GMT +5:45) Kathmandu'
},

{
name: 'Asia/Dhaka',
label: '(GMT +6:00) Astana, Dhaka, Sri Jayawardenepura'
label: '(GMT +6:00) Dhaka'
},
{
name: 'Asia/Rangoon',
label: '(GMT +6:30) Rangoon'
label: '(GMT +6:30) Yangon (Rangoon)'
},
{
name: 'Asia/Bangkok',
label: '(GMT +7:00) Bangkok, Hanoi, Jakarta'
},
{
name: 'Asia/Krasnoyarsk',
label: '(GMT +7:00) Krasnoyarsk'
label: '(GMT +7:00) Krasnoyarsk,Novosibirsk'
Comment on lines 224 to +225
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suggestion (blocking): Instead of adding Novosibirsk here to Asia/Krasnoyarsk, can we add Asia/Novosibirsk as its own item?

I did some brief reading and the history is pretty confusing, but I think they each have their own time zone identifier even if they currently observe the same times year-round.

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@niranjan-uma-shankar niranjan-uma-shankar Aug 12, 2025 •
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I initially considered adding Asia/Novosibirsk as its own item, but felt the current grouping better aligns with the original intent behind this curated timezone list (see historical context section).

In short, here's my thinking:

  • The list was merged in May 2016 when Novosibirsk had a different timezone. It moved to its current timezone shortly after (in July 2016), but the change wasn’t reflected here.
  • The list is intentionally kept small to avoid overwhelming users. Extra items add up over time.
  • We already group cities that share a timezone. Examples:
    • Rome is grouped under Europe/Amsterdam, even though it has its own canonical identifier Europe/Rome.
    • Madrid is grouped under Europe/Paris, even though it has its own canonical identifier Europe/Madrid.
  • /settings has search for the timezone dropdown, so typing “Novosibirsk” will still find it even if it's grouped and not a separate item.
  • Grouping by country/timezone feels logical, and a separate entry would mainly help with auto-timezone detection, but even that could be implemented without adding new items.

That’s my reasoning, but I’m happy to revisit if you feel strongly about keeping Novosibirsk separate.

},
{
name: 'Asia/Hong_Kong',
label: '(GMT +8:00) Beijing, Chongqing, Hong Kong, Urumqi'
},
{
name: 'Asia/Irkutsk',
label: '(GMT +8:00) Irkutsk, Ulaan Bataar'
label: '(GMT +8:00) Irkutsk, Ulaanbaatar'
},
{
name: 'Asia/Singapore',
Expand Down