diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2e5a4424..68ce46e1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - The first extent in a Collection is always the overall extent, followed by more specific extents. ([#1064](https://github.com/radiantearth/stac-spec/issues/1064), [opengeospatial/ogcapi-features#520](https://github.com/opengeospatial/ogcapi-features/pull/520))
 - Updated examples for automatic collection creation from code and validation ([#1080](https://github.com/radiantearth/stac-spec/pull/1080)
 - Clarified that stac_extensions should also list extensions that are used in Collection summaries. ([#1077](https://github.com/radiantearth/stac-spec/issues/1077))
+- `changed`, `created` (common metadata) and temporal extents (collections): Timestamps must be always in UTC ([#1095](https://github.com/radiantearth/stac-spec/issues/1095))
 
 ## [v1.0.0-rc.2] - 2021-03-30
 
diff --git a/collection-spec/collection-spec.md b/collection-spec/collection-spec.md
index f4e331c7..c76be328 100644
--- a/collection-spec/collection-spec.md
+++ b/collection-spec/collection-spec.md
@@ -197,7 +197,7 @@ Clients only interested in the overall extent will only need to access the first
 It is recommended to only use multiple temporal extents if a union of them would then include a large
 uncovered time span (e.g. only having data for the years 2000, 2010 and 2020).
 
-Each inner array consists of exactly two dates and times.
+Each inner array consists of exactly two dates and times, each in UTC.
 Each date and time MUST be formatted according to [RFC 3339, section 5.6](https://tools.ietf.org/html/rfc3339#section-5.6).
 The temporal reference system is the Gregorian calendar.
 
diff --git a/collection-spec/json-schema/collection.json b/collection-spec/json-schema/collection.json
index 422385f2..19bb9611 100644
--- a/collection-spec/json-schema/collection.json
+++ b/collection-spec/json-schema/collection.json
@@ -153,7 +153,8 @@
                         "string",
                         "null"
                       ],
-                      "format": "date-time"
+                      "format": "date-time",
+                      "pattern": "(\\+00:00|Z)$"
                     }
                   }
                 }
diff --git a/item-spec/common-metadata.md b/item-spec/common-metadata.md
index 07df2234..d5326d76 100644
--- a/item-spec/common-metadata.md
+++ b/item-spec/common-metadata.md
@@ -43,8 +43,8 @@ Fields to provide additional temporal information such as ranges with a start an
 | Field Name | Type         | Description |
 | ---------- | ------------ | ----------- |
 | datetime   | string\|null | See the [Item Spec Fields](item-spec.md#properties-object) for more information. |
-| created    | string       | Creation date and time of the corresponding data (see below). |
-| updated    | string       | Date and time the corresponding data (see below) was updated last. |
+| created    | string       | Creation date and time of the corresponding data (see below), in UTC. |
+| updated    | string       | Date and time the corresponding data (see below) was updated last, in UTC. |
 
 All timestamps MUST be formatted according to [RFC 3339, section 5.6](https://tools.ietf.org/html/rfc3339#section-5.6).
 
diff --git a/item-spec/json-schema/datetime.json b/item-spec/json-schema/datetime.json
index 3a1480db..fa540a32 100644
--- a/item-spec/json-schema/datetime.json
+++ b/item-spec/json-schema/datetime.json
@@ -20,29 +20,34 @@
       "title": "Date and Time",
       "description": "The searchable date/time of the assets, in UTC (Formatted in RFC 3339) ",
       "type": ["string", "null"],
-      "format": "date-time"
+      "format": "date-time",
+      "pattern": "(\\+00:00|Z)$"
     },
     "start_datetime": {
       "title": "Start Date and Time",
       "description": "The searchable start date/time of the assets, in UTC (Formatted in RFC 3339) ",
       "type": "string",
-      "format": "date-time"
+      "format": "date-time",
+      "pattern": "(\\+00:00|Z)$"
     }, 
     "end_datetime": {
       "title": "End Date and Time", 
       "description": "The searchable end date/time of the assets, in UTC (Formatted in RFC 3339) ",                  
       "type": "string",
-      "format": "date-time"
+      "format": "date-time",
+      "pattern": "(\\+00:00|Z)$"
     },
     "created": {
       "title": "Creation Time",
       "type": "string",
-      "format": "date-time"
+      "format": "date-time",
+      "pattern": "(\\+00:00|Z)$"
     },
     "updated": {
       "title": "Last Update Time",
       "type": "string",
-      "format": "date-time"
+      "format": "date-time",
+      "pattern": "(\\+00:00|Z)$"
     }
   }
 }
\ No newline at end of file