diff --git a/docs/source/releasenotes/0.13.2.rst b/docs/source/releasenotes/0.13.2.rst
index e9175358b..b0c9b0691 100644
--- a/docs/source/releasenotes/0.13.2.rst
+++ b/docs/source/releasenotes/0.13.2.rst
@@ -14,7 +14,7 @@ Notably, a capability has been added to compute the photon spectra from decay of
unstable nuclides. Alongside that, a new :data:`openmc.config` configuration
variable has been introduced that allows easier configuration of data sources.
Additionally, users can now perform cell or material rejection when sampling
-external source distributions. Finally,
+external source distributions.
------------------------------------
Compatibility Notes and Deprecations
diff --git a/docs/source/releasenotes/0.13.3.rst b/docs/source/releasenotes/0.13.3.rst
new file mode 100644
index 000000000..c2debbcb3
--- /dev/null
+++ b/docs/source/releasenotes/0.13.3.rst
@@ -0,0 +1,134 @@
+====================
+What's New in 0.13.3
+====================
+
+.. currentmodule:: openmc
+
+-------
+Summary
+-------
+
+This release of OpenMC includes many bug fixes, performance improvements, and
+several notable new features. Some of the highlights include support for MCPL
+source files, NCrystal thermal scattering materials, and a new
+:class:`openmc.stats.MeshSpatial` class that allows a source distribution to be
+specified over a mesh. Additionally, OpenMC now allows you to export your model
+as a single XML file rather than separate XML files for geometry, materials,
+settings, and tallies.
+
+------------------------------------
+Compatibility Notes and Deprecations
+------------------------------------
+
+- Atomic mass data used in :func:`openmc.data.atomic_mass` has been updated to
+ AME 2020, which results in slightly different masses.
+
+------------
+New Features
+------------
+
+- Support was added for `MCPL `_ files to be
+ used as external sources. Additionally, source points and surfaces sources can
+ be written as MCPL files instead of HDF5 files. (`#2116
+ `_)
+- Support was added for `NCrystal `_
+ thermal scattering materials. (`#2222
+ `_)
+- The :class:`~openmc.CylindricalMesh` and :class:`~openmc.SphericalMesh`
+ classes now have an ``origin`` attribute that changes the center of the mesh.
+ (`#2256 `_)
+- A new :class:`openmc.model.Polygon` class allows defining generalized 2D
+ polygons. (`#2266 `_)
+- A new :func:`openmc.data.decay_energy` function and
+ :meth:`openmc.Material.get_decay_heat` method enable determination of decay
+ heat from a single nuclide or material. (`#2287
+ `_)
+- Full models can now be written as a single XML file rather than separate
+ geometry, materials, settings, and tallies XML files. (`#2291
+ `_)
+- Discrete distributions are now sampled using alias sampling, which is O(1) in
+ time. (`#2329 `_)
+- The new :class:`openmc.stats.MeshSpatial` allows a spatial source distribution
+ to be specified with source strengths for each mesh element. (`#2334
+ `_)
+- The new :meth:`openmc.Geometry.get_surfaces_by_name` method returns a list of
+ matching surfaces in a geometry. (`#2347
+ `_)
+- A new :attr:`openmc.Settings.create_delayed_neutrons` attribute controls
+ whether delayed neutrons are created during a simulation. (`#2348
+ `_)
+- The :meth:`openmc.deplete.Results.export_to_materials` method now takes a
+ ``path`` argument. (`#2364 `_)
+- A new :meth:`openmc.EnergyFilter.get_tabular` method allows one to create a
+ tabular distribution based on tally results using an energy filter. (`#2371
+ `_)
+- Several methods in the :class:`openmc.Material` class that require a volume to
+ be set (e.g., :meth:`~openmc.Material.get_mass`) now accept a ``volume``
+ argument. (`#2412 `_)
+
+---------
+Bug Fixes
+---------
+
+- Fix for finding redundant surfaces (`#2263 `_)
+- Adds tolerance for temperatures slightly out of bounds (`#2265 `_)
+- Fix getter/setter for weight window bounds (`#2275 `_)
+- Make sure Chain.reduce preserves decay source (`#2283 `_)
+- Fix array shape for weight window bounds (`#2284 `_)
+- Fix for non-zero CDF start points in TSL data (`#2290 `_)
+- Fix a case where inelastic scattering yield is zero (`#2295 `_)
+- Prevent Compton profile out-of-bounds memory access (`#2297 `_)
+- Produce light particles from decay (`#2301 `_)
+- Fix zero runtime attributes in depletion statepoints (`#2302 `_)
+- Fix bug in openmc.Universe.get_nuclide_densities (`#2310 `_)
+- Only show print output from depletion on rank 0 (`#2311 `_)
+- Fix photon transport with no atomic relaxation data (`#2312 `_)
+- Fix for precedence in region expressions (`#2318 `_)
+- Allow source particles with energy below cutoff (`#2319 `_)
+- Fix IncidentNeutron.from_njoy for high temperatures (`#2320 `_)
+- Add capability to unset cell temperatures (`#2323 `_)
+- Fix in plot_xs when S(a,b) tables are present (`#2335 `_)
+- Various fixes for tally triggers (`#2344 `_)
+- Raise error when mesh is flat (`#2363 `_)
+- Don't call normalize inside Tabular.mean (`#2375 `_)
+- Avoid out-of-bounds access in inelastic scatter sampling (`#2378 `_)
+- Use correct direction for anisotropic fission (`#2381 `_)
+- Fix several thermal scattering nuclide assignments (`#2382 `_)
+- Fix _materials_by_id attribute in Model (`#2385 `_)
+- Updates to batch checks for simulation restarts (`#2390 `_)
+- write_data_to_vtk volume normalization correction (`#2397 `_)
+- Enable generation of JEFF 3.3 depletion chain (`#2410 `_)
+- Fix spherical to Cartesian coordinate conversion (`#2417 `_)
+- Handle zero photon cross sections in IncidentPhoton.from_ace (`#2433 `_)
+- Fix hybrid depletion when nuclides are not present (`#2436 `_)
+- Fix bug in cylindrical and spherical meshes (`#2439 `_)
+- Improvements to mesh radial boundary coincidence (`#2443 `_)
+
+------------
+Contributors
+------------
+
+- `Hunter Belanger `_
+- `Rémi Delaporte-Mathurin `_
+- `Christopher Fichtlscherer `_
+- `Valerio Giusti `_
+- `Chris Keckler `_
+- `Kalin Kiesling `_
+- `Thomas Kittelmann `_
+- `Erik Knudsen `_
+- `Colin Larmier `_
+- `Amanda Lund `_
+- `Jose Ignacio Marquez Damien `_
+- `Josh May `_
+- `Patrick Myers `_
+- `Baptiste Mouginot `_
+- `April Novak `_
+- `Matthew Nyberg `_
+- `Ethan Peterson `_
+- `Gavin Ridley `_
+- `Paul Romano `_
+- `Patrick Shriwise `_
+- `Jonathan Shimwell `_
+- `Paul Wilson `_
+- `Olek Yardas `_
+- `Jiankai Yu `_
diff --git a/docs/source/releasenotes/index.rst b/docs/source/releasenotes/index.rst
index 910737a41..30b6d51de 100644
--- a/docs/source/releasenotes/index.rst
+++ b/docs/source/releasenotes/index.rst
@@ -7,6 +7,7 @@ Release Notes
.. toctree::
:maxdepth: 1
+ 0.13.3
0.13.2
0.13.1
0.13.0