How do I check if daylight saving time is in effect?

Call GET /v1/time/dst?tz=America/New_York with your API key. The dst_active field says whether daylight saving time applies right now, alongside the timezone, UTC and local ISO values and the current offset.

Why does a fixed offset always return dst_active=false?

A fixed offset such as +02:00 is a number, not a rules-based IANA zone, so it has no daylight saving rules. Use a tz, ip or lat and lon selector to get real DST behaviour.

Can I check DST for a past or future date?

The DST endpoint always reports the current moment. To see the offset and local time at another instant, use /v1/time/convert with that timestamp.

Can I tell whether DST is active from the UTC offset alone?

No. The same offset occurs in zones with different rules, so DST status has to come from the zone, not from the number.

DST API: Check Daylight Saving Time and the Next Change

Q: How do I get the next DST change?

Add next=true. The response then includes next_transition: the instant of the next UTC offset change, written in the offset in force before it (for example 2026-03-08T02:00:00-05:00 for New York), or null when none is scheduled.

Check whether daylight saving time is active for any IANA zone, IP or coordinates, and get the next UTC offset change with next=true.

Short answer: call GET /v1/time/dst with a timezone, IP, coordinates or offset. dst_active tells you whether daylight saving time is in effect now; add next=true to get next_transition, the next UTC offset change.

curl "https://api.timelogicapi.com/v1/time/dst?tz=America/New_York&next=true" \
  -H "Authorization: Bearer $TIMELOGIC_API_KEY"

How can an API report daylight-saving time?

Call /v1/time/dst as a daylight saving time API or DST API with a timezone, IP address, coordinates, or fixed offset. The response reports whether daylight saving is active and can include the next transition when the selected zone has one. Together with the offset context it also serves as a UTC offset API or timezone offset API for the current moment.

How do I select a zone?

Use at most one selector family. A fixed offset is a numeric context rather than a rules-based IANA zone, so it always returns dst_active=false.

GET /v1/time/dst?tz=America/New_York&next=true

The same selector choices used by the timezone endpoints are available: tz, ip, lat + lon, offset, and auto_tz=true. If no selector is provided, the response is for UTC with timezone: null. URL-encode a plus sign in an offset as %2B.

How do I use the transition data safely?

Use dst_active with the returned timezone, utc, iso_local, and offset context when explaining a user's local time. If next=true is supplied, the response includes next_transition: the instant of the next UTC offset change, written in the offset in force before it (for example 2026-11-01T02:00:00-04:00), or null when none is scheduled. It tracks offset changes only, so a zone can change dst_active without one (America/Vancouver on November 1, 2026 under tzdata 2026e). The DST endpoint always reports the current moment; use convert for other dates. Do not infer DST from a numeric offset alone, because the same offset can occur in zones with different rules.

Fixed offsets do not have DST rules and return dst_active=false. Use the DST endpoint reference for parameters and signed responses when the result must be verifiable.

Daylight saving time API guide: DST status and the next transition