From 8587fdfc717f8ec9c925ba93b9cab7209820e83d Mon Sep 17 00:00:00 2001
From: Tim Parenti <tim@timtimeonline.com>
Date: Fri, 19 Jun 2026 11:41:03 -0400
Subject: Alberta's change became official on 2026-06-18

* NEWS: Mention this and update surrounding commentary.
* northamerica (America/Edmonton): Now permanently on -06.
Model this with abbreviation CST.  Although the actual transition was
legally on 2026-06-18, temporarily model the transition on 2026-11-01 at
02:00 to work around the same CLDR problems that we saw with BC.
(America/Inuvik): Update commentary to reflect the latest implications
for our Northwest Territories data.
* zone.tab, zone1970.tab: Update comments.
* zonenow.tab: New temporary entry for America/Edmonton until
2026-11-01.
---
 NEWS         | 25 ++++++++++++++++--------
 northamerica | 54 +++++++++++++++++++++++++++-------------------------
 zone.tab     |  2 +-
 zone1970.tab |  2 +-
 zonenow.tab  |  3 +++
 5 files changed, 50 insertions(+), 36 deletions(-)

diff --git a/NEWS b/NEWS
index bb912dc..042602c 100644
--- a/NEWS
+++ b/NEWS
@@ -3,8 +3,19 @@ News for the tz database
 Unreleased, experimental changes
 
   Briefly:
+    Alberta moved to permanent -06 on 2026-06-18.
     Another integer overflow bug has been fixed in zic.
 
+  Changes to future timestamps
+
+    Alberta’s 2026-03-08 spring forward was its last foreseeable clock
+    change, as it moved to permanent -06 thereafter.  (Thanks to Roozbeh
+    Pournader and others.)  Model this with its traditional abbreviation
+    CST.  Although the change to permanent -06 legally took place on
+    2026-06-18, temporarily model the change to occur on 2026-11-01 at
+    02:00 instead, for the same reason we introduced a similarly
+    temporary hack for British Columbia in 2026b.
+
   Changes to code
 
     zic no longer overflows an integer when processing outlandish
@@ -13,14 +24,12 @@ Unreleased, experimental changes
 
   Changes to commentary
 
-    The 2026-03-08 spring forward in Alberta and in Northwest
-    Territories was likely the last foreseeable clock change there,
-    as these areas are expected to move to permanent -06 thereafter.
-    (Thanks to Roozbeh Pournader and others.)  This will affect UT
-    offsets starting 2026-11-01 02:00, when clocks would otherwise
-    fall back.  Model this with its traditional abbreviation CST.
-    Unfortunately the change is not yet official, so it is currently
-    present only as comments that can be uncommented as needed.
+    Northwest Territories is expected to move to permanent -06 prior to
+    2026-11-01 02:00, when clocks would otherwise fall back.  (Thanks to
+    Tim Parenti and James Bellaire.)  Model this with its traditional
+    abbreviation CST.  Unfortunately the change is not yet official, so
+    it is currently present only as comments that can be uncommented as
+    needed.
 
   Changes to build procedure
 
diff --git a/northamerica b/northamerica
index 7297301..4ae6f45 100644
--- a/northamerica
+++ b/northamerica
@@ -1933,29 +1933,28 @@ Zone America/Swift_Current -7:11:20 -	LMT	1905 Sep
 # https://calgaryherald.com/opinion/columnists/bell-alberta-daylight-time-year-round-premier-danielle-smith
 #
 # From Tim Parenti (2026-04-23):
-# Bill 31, the Red Tape Reduction Statutes Amendment Act, 2026
+# Section 3 of Bill 31, the Red Tape Reduction Statutes Amendment Act, 2026
 # https://docs.assembly.ab.ca/LADDAR_files/docs/bills/bill/legislature_31/session_2/20251023_bill-031.pdf
 # would repeal the Daylight Saving Time Act in the Revised Statues of Alberta
 # 2000 Chapter D-5:
 # https://kings-printer.alberta.ca/documents/Acts/D05.pdf
 # ...and substitutes a new chapter with language that closely parallels the
-# original.  The new title is the Official Time Act and would be numbered
-# Chapter O-5.7.  The bill would establish a standard time of UTC−6 without
+# original.  The new title is the Official Time Act and will be numbered
+# Chapter O-5.7.  The Act establishes a standard time of UTC−6 without
 # replacing the language previously used to effectuate DST.
 #
-# From Tim Parenti (2026-05-14):
-# Royal Assent...was announced this morning.  The stated intent of Alberta's
-# government has been to have this in place prior to when the clocks would
-# otherwise fall back on 2026-11-01.  For now, use that date pending the Order
-# in Council.  This also works around potential CLDR limitations in the
-# meantime; see British Columbia, below.
-#
-# From Paul Eggert (2026-06-12):
-# Need a legal citation for the official 2026 change to the law.  The bill
-# specifies UT offset only; abbreviate it as CST for consistency.  It requires
-# an Order in Council signed by the Lieutenant Governor before it becomes
-# legally binding.  As this has not yet happened, the changes are commented
-# out for now in America/Edmonton.  Similarly for America/Inuvik.
+# From Tim Parenti (2026-06-19):
+# After receiving Royal Assent on 2026-05-14, Order in Council 204/2026 was
+# issued on 2026-06-18 proclaiming the relevant section of the bill in force on
+# the same date.  Order in Council 206/2026, issued the same day, uses the
+# regulatory authority within the Act to prescribe the official term "Alberta
+# Time"; we use the traditional abbreviation CST for consistency.
+# https://kings-printer.alberta.ca/Documents/Orders/Orders_in_Council/2026/2026_204.pdf
+# https://kings-printer.alberta.ca/Documents/Orders/Orders_in_Council/2026/2026_206.pdf
+#
+# Since wall clock times do not diverge from past practice until 2026-11-01,
+# use that transition date for now to work around potential CLDR limitations in
+# the meantime; see British Columbia, below.
 
 # Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
 Rule	Edm	1918	1919	-	Apr	Sun>=8	2:00	1:00	D
@@ -1974,11 +1973,11 @@ Rule	Edm	1972	2006	-	Oct	lastSun	2:00	0	S
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Edmonton	-7:33:52 -	LMT	1906 Sep
 			-7:00	Edm	M%sT	1987
-			-7:00	Canada	M%sT
-# Assuming the relevant part of Red Tape Reduction Statutes Amendment Act, 2026
-# takes effect on 2026-11-01 at 02:00, replace the above line with:
-#			-7:00	Canada	M%sT	2026 Nov  1  2:00
-#			-6:00	-	CST
+			-7:00	Canada	M%sT	2026 Jun 18
+			# Temporary hack; see above.
+			-7:00	1:00	MDT	2026 Nov  1  2:00
+			# End of temporary hack.
+			-6:00	-	CST
 
 
 # British Columbia
@@ -2420,12 +2419,15 @@ Zone America/Fort_Nelson	-8:10:47 -	LMT	1884
 # end seasonal time changes until Alberta does."
 # https://www.cbc.ca/news/canada/north/nwt-ends-daylight-saving-9.7170964
 #
-# From Tim Parenti (2026-06-11), per James Bellaire (2026-06-02):
-# Much of NWT is currently represented by America/Edmonton, which alias
+# From Tim Parenti (2026-06-19), per James Bellaire (2026-06-02):
+# Much of NWT has, to date, been represented by America/Edmonton, which alias
 # America/Yellowknife links to.  While Bill 13 (assented to 2021-03-31) would
 # enable NWT's proposed change mirroring Alberta's, at time of writing it has
 # not yet been formally enacted; if it doesn't move forward as expected,
-# America/Yellowknife would need to become its own zone.
+# America/Yellowknife would need to become its own zone as Alberta has stopped
+# changing its clocks.
+# If it does go ahead, draft changes to America/Inuvik, which represents the
+# remainder of NWT, are commented below.
 
 # Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
 Rule	NT_YK	1918	only	-	Apr	14	2:00	1:00	D
@@ -2469,8 +2471,8 @@ Zone America/Inuvik	0	-	-00	1953 # Inuvik founded
 			-8:00	NT_YK	P%sT	1979 Apr lastSun  2:00
 			-7:00	NT_YK	M%sT	1980
 			-7:00	Canada	M%sT
-# Assuming Alberta stops changing clocks in fall 2026 and Northwest Territories
-# follow Alberta, replace the above line with:
+# Assuming Northwest Territories follow Alberta in abolishing seasonal time
+# changes, replace the above line with something like:
 #			-7:00	Canada	M%sT	2026 Nov  1  2:00
 #			-6:00	-	CST
 Zone America/Whitehorse	-9:00:12 -	LMT	1900 Aug 20
diff --git a/zone.tab b/zone.tab
index 2ae8a8c..69d50bd 100644
--- a/zone.tab
+++ b/zone.tab
@@ -121,7 +121,7 @@ CA	+744144-0944945	America/Resolute	Central - NU (Resolute)
 CA	+624900-0920459	America/Rankin_Inlet	Central - NU (central)
 CA	+5024-10439	America/Regina	CST - SK (most areas)
 CA	+5017-10750	America/Swift_Current	CST - SK (midwest)
-CA	+5333-11328	America/Edmonton	Mountain - AB, BC(E), NT(E), SK(W)
+CA	+5333-11328	America/Edmonton	CST - AB, BC(E), NT(E), SK(W)
 CA	+690650-1050310	America/Cambridge_Bay	Mountain - NU (west)
 CA	+682059-1334300	America/Inuvik	Mountain - NT (west)
 CA	+4916-12307	America/Vancouver	MST - BC (most areas)
diff --git a/zone1970.tab b/zone1970.tab
index a9b47bc..635eabc 100644
--- a/zone1970.tab
+++ b/zone1970.tab
@@ -112,7 +112,7 @@ CA	+744144-0944945	America/Resolute	Central - NU (Resolute)
 CA	+624900-0920459	America/Rankin_Inlet	Central - NU (central)
 CA	+5024-10439	America/Regina	CST - SK (most areas)
 CA	+5017-10750	America/Swift_Current	CST - SK (midwest)
-CA	+5333-11328	America/Edmonton	Mountain - AB, BC(E), NT(E), SK(W)
+CA	+5333-11328	America/Edmonton	CST - AB, BC(E), NT(E), SK(W)
 CA	+690650-1050310	America/Cambridge_Bay	Mountain - NU (west)
 CA	+682059-1334300	America/Inuvik	Mountain - NT (west)
 CA	+4916-12307	America/Vancouver	MST - BC (most areas)
diff --git a/zonenow.tab b/zonenow.tab
index c499cc8..e6babe8 100644
--- a/zonenow.tab
+++ b/zonenow.tab
@@ -67,6 +67,9 @@ XX	+332654-1120424	America/Phoenix	Mountain Standard (MST) - Arizona; western Me
 # -07/-06 - MST/MDT (North America DST)
 XX	+394421-1045903	America/Denver	Mountain (MST/MDT) - US & Canada; Mexico near US border
 #
+# -07/-06 - MST/MDT (North America DST) until 2026-11-01 02:00; then CST
+XX	+5333-11328	America/Edmonton	Central Standard (CST) - Alberta and some neighbors
+#
 # -06
 XX	-0054-08936	Pacific/Galapagos	Galápagos
 #
-- 
2.50.1 (Apple Git-155)

