Technical Specifications & Standards
Official chronometric properties, ISO standards, and international database registry identifiers for Chile Summer Time:
Daylight Saving Time (DST) Transitions
⬆️ Spring Forward (Clocks Advance)
First Saturday in September at 24:00 / midnight (Continental clocks advance to CLST)
⬇️ Fall Back (Clocks Return)
First Saturday in April at 24:00 / midnight (Continental clocks return to CLT)
Observing Jurisdictions & Subdivisions
1 Sovereign NationsSovereign nations, administrative subdivisions, and regional territories officially operating under CLST:
Regional Subdivisions & Territory Details
Financial Markets & Trading Hours
During southern summer, Santiago trading desks share the same UTC-3 offset as São Paulo and Buenos Aires, enabling synchronized Latin American equity book building.
Local Hours: 09:30 - 16:00 CLST
UTC Window: 12:30 - 19:00 UTC
Major Cities in CLST
Primary metropolitan centers and financial hubs observing this time zone:
Adoption History & Astronomical Facts
Year Established: 1970
Formalized by supreme decree under the Ministry of the Interior in 1970 to curb electrical peak loads during summer evenings. The exact start and finish dates have occasionally been shifted by special executive decrees to accommodate national elections or census operations.
During Chile Summer Time, Santiago shares the exact same clock time as Buenos Aires, Argentina, and São Paulo, Brazil, allowing cross-border commercial flights across the Andes to land without any time difference.
Frequently Asked Questions about CLST
What is the difference between CLST and CLT?
CLST (Chile Summer Time) is the daylight saving offset (UTC-3) observed between September and April, while CLT (Chile Standard Time) is the winter standard time (UTC-4) used between April and September.
Is Santiago ahead of New York during CLST?
During the Northern Hemisphere winter (when New York uses EST, UTC-5), Santiago on CLST (UTC-3) is 2 hours ahead of New York. In late March, when New York enters EDT (UTC-4), Santiago is 1 hour ahead until Chile's April clock change.
Does Easter Island use CLST?
No. Easter Island uses Easter Island Summer Time (EASST, UTC-5) during the summer months, staying exactly two hours behind continental Chile.