[{"data":1,"prerenderedAt":169},["ShallowReactive",2],{"page:\u002Fen\u002Fguides\u002Ftime-zones-and-dst":3},{"id":4,"title":5,"body":6,"description":150,"extension":151,"faq":152,"intro":159,"kind":160,"locale":161,"meta":162,"navigation":163,"path":164,"seo":165,"seoTitle":166,"stem":167,"__hash__":168},"pages\u002Fen\u002Fguides\u002Ftime-zones-and-dst.md","Understand time zones and daylight saving",{"type":7,"value":8,"toc":141},"minimark",[9,14,26,35,39,83,86,90,93,96,100,108,111,115],[10,11,13],"h2",{"id":12},"a-zone-is-a-rule-set-not-a-fixed-number","A zone is a rule set, not a fixed number",[15,16,17,21,22,25],"p",{},[18,19,20],"code",{},"America\u002FNew_York"," and ",[18,23,24],{},"Europe\u002FLondon"," are IANA identifiers. They describe regional rules over time. UTC−05:00 or UTC+01:00 is only an offset at a particular instant. Time-zone abbreviations are not unique worldwide, so keep the IANA identifier when communicating a location.",[15,27,28,29,34],{},"New York uses UTC−05:00 in standard time and UTC−04:00 during daylight saving. London uses UTC+00:00 and UTC+01:00. Their clock changes do not always occur in the same week. In 2026, New York at noon on March 10 corresponds to London at 16:00; noon on March 31 corresponds to 17:00. Check the actual date in the ",[30,31,33],"a",{"href":32},"\u002Ftime-converter\u002F","converter",".",[10,36,38],{"id":37},"some-clocks-skip-or-repeat-a-local-time","Some clocks skip or repeat a local time",[40,41,42,55],"table",{},[43,44,45],"thead",{},[46,47,48,52],"tr",{},[49,50,51],"th",{},"New York local input",[49,53,54],{},"Interpretation",[56,57,58,67,75],"tbody",{},[46,59,60,64],{},[61,62,63],"td",{},"2024-03-10 02:30",[61,65,66],{},"Missing during the spring jump",[46,68,69,72],{},[61,70,71],{},"2024-11-03 01:30 at UTC−04:00",[61,73,74],{},"First occurrence: 05:30 UTC",[46,76,77,80],{},[61,78,79],{},"2024-11-03 01:30 at UTC−05:00",[61,81,82],{},"Second occurrence: 06:30 UTC",[15,84,85],{},"A local date and time therefore does not always identify exactly one instant. Reject skipped times; ask for an offset when a time repeats. A selected calendar day can have 23 or 25 elapsed hours, so an accurate meeting timeline must not assume 24 equal hourly positions every day.",[10,87,89],{"id":88},"fractions-of-an-hour-and-date-changes","Fractions of an hour and date changes",[15,91,92],{},"Kathmandu uses UTC+05:45. Adelaide uses UTC+09:30 in standard time and UTC+10:30 during daylight saving. A converter must support these minute offsets rather than round them to whole hours.",[15,94,95],{},"At 2026-12-31 23:30 in Kathmandu, Adelaide reads 2027-01-01 04:15. The year changes in the destination even though both clocks show the same instant. Always communicate a date as well as an hour.",[10,97,99],{"id":98},"plan-meetings-using-the-whole-duration","Plan meetings using the whole duration",[15,101,102,103,107],{},"The ",[30,104,106],{"href":105},"\u002Fmeeting-planner\u002F","meeting planner"," turns each city’s working periods into absolute intervals, then checks the entire proposed meeting against those intervals. A convenient start alone is insufficient. Weekends and crossing midnight can change a result; work-hour suitability is not a claim about a participant’s real availability.",[15,109,110],{},"For a future recurring event, preserve the region’s zone and its intended local time. Future governments can change rules, and browser time-zone data may lag new decisions. This site uses available browser rules and device time; it does not provide official legal time guarantees.",[10,112,114],{"id":113},"technical-references","Technical references",[116,117,118,127,134],"ul",{},[119,120,121],"li",{},[30,122,126],{"href":123,"rel":124},"https:\u002F\u002Fwww.iana.org\u002Ftime-zones",[125],"nofollow","IANA Time Zone Database",[119,128,129],{},[30,130,133],{"href":131,"rel":132},"https:\u002F\u002Fdeveloper.mozilla.org\u002Fen-US\u002Fdocs\u002FWeb\u002FJavaScript\u002FReference\u002FGlobal_Objects\u002FTemporal\u002FZonedDateTime",[125],"MDN: Temporal.ZonedDateTime",[119,135,136],{},[30,137,140],{"href":138,"rel":139},"https:\u002F\u002Fwww.rfc-editor.org\u002Frfc\u002Frfc5545",[125],"RFC 5545 calendar events",{"title":142,"searchDepth":143,"depth":143,"links":144},"",2,[145,146,147,148,149],{"id":12,"depth":143,"text":13},{"id":37,"depth":143,"text":38},{"id":88,"depth":143,"text":89},{"id":98,"depth":143,"text":99},{"id":113,"depth":143,"text":114},"Learn how IANA zones, UTC offsets, daylight-saving gaps and repeated times affect city clocks, date conversion and global meetings.","md",[153,156],{"question":154,"answer":155},"Is a UTC offset the same as a time zone?","No. An offset is a difference at one instant. An IANA zone contains regional rules that can change that offset across dates.",{"question":157,"answer":158},"Why can London and New York differ by four or five hours?","The US and Europe change their clocks on different dates. During the intervening weeks, their usual difference changes.",null,"guide","en",{},true,"\u002Fen\u002Fguides\u002Ftime-zones-and-dst",{"title":5,"description":150},"Time Zones and DST — Offsets, Missing Times and Meeting Planning","en\u002Fguides\u002Ftime-zones-and-dst","UpXnTOGcZVshTp1dUTzRi-haiZ30TUwTlT8eQKuiCaI",1792030944943]