diff --git a/.github/workflows/benchmarks.yml b/.github/workflows/benchmarks.yml
index 0ae9e4cfd82..d378c8b758a 100644
--- a/.github/workflows/benchmarks.yml
+++ b/.github/workflows/benchmarks.yml
@@ -55,7 +55,7 @@ jobs:
           # environment cache is persistent for one week.
           cache-environment-key: micromamba-environment-${{ steps.date.outputs.date }}
           create-args: >-
-            gmt=6.5.0
+            gmt=6.6.0
             python=3.13
             numpy
             pandas
diff --git a/.github/workflows/cache_data.yaml b/.github/workflows/cache_data.yaml
index 2bc0a1e39c4..7ee84f92e59 100644
--- a/.github/workflows/cache_data.yaml
+++ b/.github/workflows/cache_data.yaml
@@ -51,7 +51,7 @@ jobs:
           environment-name: pygmt
           create-args: >-
             python=3.13
-            gmt=6.5.0
+            gmt=6.6.0
             numpy
             pandas
             xarray
diff --git a/.github/workflows/ci_docs.yml b/.github/workflows/ci_docs.yml
index 7b4e078dd92..c4c15787eb3 100644
--- a/.github/workflows/ci_docs.yml
+++ b/.github/workflows/ci_docs.yml
@@ -91,7 +91,7 @@ jobs:
           cache-environment-key: micromamba-environment-${{ steps.date.outputs.date }}
           create-args: >-
             python=3.13
-            gmt=6.5.0
+            gmt=6.6.0
             ghostscript=10.06.0
             numpy
             pandas
diff --git a/.github/workflows/ci_doctests.yaml b/.github/workflows/ci_doctests.yaml
index 506c6bf1bd3..ab56dab2ea0 100644
--- a/.github/workflows/ci_doctests.yaml
+++ b/.github/workflows/ci_doctests.yaml
@@ -50,7 +50,7 @@ jobs:
           environment-name: pygmt
           create-args: >-
             python=3.13
-            gmt=6.5.0
+            gmt=6.6.0
             numpy
             pandas
             xarray
diff --git a/.github/workflows/ci_tests.yaml b/.github/workflows/ci_tests.yaml
index 739f4c57e52..2038ad5c7c0 100644
--- a/.github/workflows/ci_tests.yaml
+++ b/.github/workflows/ci_tests.yaml
@@ -124,7 +124,7 @@ jobs:
           cache-environment-key: micromamba-environment-${{ steps.date.outputs.date }}
           create-args: >-
             python=${{ matrix.python-version }}${{ matrix.optional-packages }}
-            gmt=6.5.0
+            gmt=6.6.0
             ghostscript=10.06.0
             numpy=${{ matrix.numpy-version }}
             pandas${{ matrix.pandas-version }}
diff --git a/.github/workflows/ci_tests_legacy.yaml b/.github/workflows/ci_tests_legacy.yaml
index 716380f0db2..aa9942b0d6a 100644
--- a/.github/workflows/ci_tests_legacy.yaml
+++ b/.github/workflows/ci_tests_legacy.yaml
@@ -37,7 +37,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-22.04, ubuntu-22.04-arm, macos-14, windows-2022]
-        gmt_version: ['6.4']
+        gmt_version: ['6.4', '6.5']
     timeout-minutes: 30
     defaults:
       run:
diff --git a/ci/requirements/docs.yml b/ci/requirements/docs.yml
index a745bd99215..879ea6bc7bf 100644
--- a/ci/requirements/docs.yml
+++ b/ci/requirements/docs.yml
@@ -5,7 +5,7 @@ channels:
 dependencies:
     # Required dependencies
     - python=3.13
-    - gmt=6.5.0
+    - gmt=6.6.0
     - ghostscript=10.06.0
     - numpy
     - pandas
diff --git a/doc/conf.py b/doc/conf.py
index c3a7bd78562..c9558797ceb 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -101,8 +101,8 @@
 
 # Options for extlinks.
 extlinks = {
-    "gmt-docs": ("https://docs.generic-mapping-tools.org/6.5/%s", None),
-    "gmt-term": ("https://docs.generic-mapping-tools.org/6.5/gmt.conf#term-%s", "%s"),
+    "gmt-docs": ("https://docs.generic-mapping-tools.org/6.6/%s", None),
+    "gmt-term": ("https://docs.generic-mapping-tools.org/6.6/gmt.conf#term-%s", "%s"),
     "gmt-datasets": ("https://www.generic-mapping-tools.org/remote-datasets/%s", None),
 }
 
diff --git a/environment.yml b/environment.yml
index f5539983e08..5ab8f6cb94b 100644
--- a/environment.yml
+++ b/environment.yml
@@ -5,7 +5,7 @@ channels:
 dependencies:
     - python>=3.11
     # Required dependencies
-    - gmt=6.5.0
+    - gmt=6.6.0
     - ghostscript=10.06.0
     - numpy>=1.26
     - pandas>=2.2