diff --git a/crates/uv-settings/src/settings.rs b/crates/uv-settings/src/settings.rs
index ed86147f747f0..7c2406d0c71ac 100644
--- a/crates/uv-settings/src/settings.rs
+++ b/crates/uv-settings/src/settings.rs
@@ -607,16 +607,16 @@ pub struct ResolverInstallerOptions {
     "#
     )]
     pub no_build_isolation_package: Option<Vec<PackageName>>,
-    /// Limit candidate packages to those that were uploaded prior to the given date.
+    /// Limit candidate packages to those that were uploaded prior to a given point in time.
     ///
-    /// Accepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g.,
-    /// `2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`) in your
-    /// system's configured time zone.
+    /// Accepts a superset of [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) (e.g.,
+    /// `2006-12-02T02:07:43Z`). A full timestamp is required to ensure that the resolver will
+    /// behave consistently across timezones.
     #[option(
         default = "None",
         value_type = "str",
         example = r#"
-            exclude-newer = "2006-12-02"
+            exclude-newer = "2006-12-02T02:07:43Z"
         "#
     )]
     pub exclude_newer: Option<ExcludeNewer>,
diff --git a/docs/reference/settings.md b/docs/reference/settings.md
index 5de24e84ab0ec..b483966808d63 100644
--- a/docs/reference/settings.md
+++ b/docs/reference/settings.md
@@ -960,11 +960,11 @@ standard, though only the following fields are respected:
 
 ### [`exclude-newer`](#exclude-newer) {: #exclude-newer }
 
-Limit candidate packages to those that were uploaded prior to the given date.
+Limit candidate packages to those that were uploaded prior to a given point in time.
 
-Accepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g.,
-`2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`) in your
-system's configured time zone.
+Accepts a superset of [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) (e.g.,
+`2006-12-02T02:07:43Z`). A full timestamp is required to ensure that the resolver will
+behave consistently across timezones.
 
 **Default value**: `None`
 
@@ -976,12 +976,12 @@ system's configured time zone.
 
     ```toml
     [tool.uv]
-    exclude-newer = "2006-12-02"
+    exclude-newer = "2006-12-02T02:07:43Z"
     ```
 === "uv.toml"
 
     ```toml
-    exclude-newer = "2006-12-02"
+    exclude-newer = "2006-12-02T02:07:43Z"
     ```
 
 ---
diff --git a/uv.schema.json b/uv.schema.json
index fff7d8a4799e8..54d5a0c748cfc 100644
--- a/uv.schema.json
+++ b/uv.schema.json
@@ -182,7 +182,7 @@
       }
     },
     "exclude-newer": {
-      "description": "Limit candidate packages to those that were uploaded prior to the given date.\n\nAccepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g., `2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`) in your system's configured time zone.",
+      "description": "Limit candidate packages to those that were uploaded prior to a given point in time.\n\nAccepts a superset of [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) (e.g., `2006-12-02T02:07:43Z`). A full timestamp is required to ensure that the resolver will behave consistently across timezones.",
       "anyOf": [
         {
           "$ref": "#/definitions/ExcludeNewer"