Offsets and DST
TZ_IS_DST
Checks whether daylight saving time is active in a zone.
Syntax
=TZ_IS_DST(zone, [datetime])Parameters
NameTypeDescription
Name
zoneTypetext
DescriptionIANA time zone to evaluate.
Name
datetime?Typetext, number, or date
DescriptionInstant to evaluate. Defaults to now.
Returns
TRUE when daylight saving time is active, otherwise FALSE.
Example
=TZ_IS_DST("America/New_York", "2026-07-01")Result: TRUE