diff --git a/dev-requirements.txt b/dev-requirements.txt
index f305175c..9d5bb621 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -252,7 +252,7 @@ pytest-mock==3.12.0
     # via swmmanywhere (pyproject.toml)
 pytest-mypy==0.10.3
     # via swmmanywhere (pyproject.toml)
-python-dateutil==2.8.2
+python-dateutil==2.9.0.post0
     # via
     #   matplotlib
     #   pandas
diff --git a/requirements.txt b/requirements.txt
index a165c532..1c0fc6ec 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -198,7 +198,7 @@ pysheds==0.3.5
     # via swmmanywhere (pyproject.toml)
 pyswmm==1.5.1
     # via swmmanywhere (pyproject.toml)
-python-dateutil==2.8.2
+python-dateutil==2.9.0.post0
     # via
     #   matplotlib
     #   pandas