diff --git a/docs/sphinx/source/whatsnew/v0.9.1.rst b/docs/sphinx/source/whatsnew/v0.9.1.rst
index 64fc94cfa1..1d8862d67f 100644
--- a/docs/sphinx/source/whatsnew/v0.9.1.rst
+++ b/docs/sphinx/source/whatsnew/v0.9.1.rst
@@ -29,6 +29,9 @@ Testing
 
 Documentation
 ~~~~~~~~~~~~~
+* Fix documentation return error in :py:meth:`pvlib.forecast.ForecastModel.cloud_cover_to_transmittance_linear`
+  (:issue:`1367`, :pull:`1370`)
+
 
 Requirements
 ~~~~~~~~~~~~
@@ -41,3 +44,4 @@ Contributors
 * Christian Weickhmann (:ghuser:`cweickhmann`)
 * Kevin Anderson (:ghuser:`kanderso-nrel`)
 * Adam R. Jensen (:ghuser:`AdamRJensen`)
+* Johann Loux (:ghuser:`JoLo90`)
diff --git a/pvlib/forecast.py b/pvlib/forecast.py
index 4b90ca3e05..634ae75ab2 100644
--- a/pvlib/forecast.py
+++ b/pvlib/forecast.py
@@ -512,10 +512,10 @@ def cloud_cover_to_irradiance_clearsky_scaling(self, cloud_cover,
     def cloud_cover_to_transmittance_linear(self, cloud_cover, offset=0.75,
                                             **kwargs):
         """
-        Convert cloud cover to atmospheric transmittance using a linear
-        model.
+        Convert cloud cover (percentage) to atmospheric transmittance
+        using a linear model.
 
-        0% cloud cover returns offset.
+        0% cloud cover returns "offset".
 
         100% cloud cover returns 0.
 
@@ -524,14 +524,15 @@ def cloud_cover_to_transmittance_linear(self, cloud_cover, offset=0.75,
         cloud_cover : numeric
             Cloud cover in %.
         offset : numeric, default 0.75
-            Determines the maximum transmittance.
+            Determines the maximum transmittance. [unitless]
         kwargs
             Not used.
 
         Returns
         -------
-        ghi : numeric
-            Estimated GHI.
+        transmittance : numeric
+            The fraction of extraterrestrial irradiance that reaches
+            the ground. [unitless]
         """
         transmittance = ((100.0 - cloud_cover) / 100.0) * offset