diff --git a/docs/sphinx/source/reference/iotools.rst b/docs/sphinx/source/reference/iotools.rst
index 8e2a3034d2..dcae9ba926 100644
--- a/docs/sphinx/source/reference/iotools.rst
+++ b/docs/sphinx/source/reference/iotools.rst
@@ -9,23 +9,62 @@ IO Tools
 ========
 
 Functions for retrieving, reading, and writing data from a variety
-of sources and file formats relevant to solar energy modeling.
+of sources and file formats relevant to solar energy modeling.  See also
+:ref:`weatherdata`.
+
+.. contents:: Currently supported APIs
+    :depth: 3
+    :local:
+
+
+Gridded resource data
+---------------------
+
+Modeled irradiance and meteorological data, available for large regions of
+the world.
+
+Public datasets
+^^^^^^^^^^^^^^^
+
+These APIs are free to access, although some require registration.
+
+PVGIS
+*****
+
+Multiple gridded irradiance and weather datasets with global coverage.
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.get_pvgis_tmy
+   iotools.read_pvgis_tmy
+   iotools.get_pvgis_hourly
+   iotools.read_pvgis_hourly
+   iotools.get_pvgis_horizon
+
+
+CAMS
+****
+
+Satellite-derived irradiance data for Europe, Africa, and Asia, and
+clear-sky irradiance globally.
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.get_cams
+   iotools.read_cams
+   iotools.parse_cams
+
+
+NSRDB
+*****
+
+Satellite-derived irradiance and weather data for the Americas.
 
 .. autosummary::
    :toctree: generated/
 
-   iotools.read_tmy2
-   iotools.read_tmy3
-   iotools.read_epw
-   iotools.parse_epw
-   iotools.read_srml
-   iotools.get_srml
-   iotools.read_surfrad
-   iotools.read_midc
-   iotools.read_midc_raw_data_from_nrel
-   iotools.read_crn
-   iotools.read_solrad
-   iotools.get_solrad
    iotools.get_nsrdb_psm4_aggregated
    iotools.get_nsrdb_psm4_tmy
    iotools.get_nsrdb_psm4_conus
@@ -35,30 +74,156 @@ of sources and file formats relevant to solar energy modeling.
    iotools.get_psm3
    iotools.read_psm3
    iotools.parse_psm3
-   iotools.get_pvgis_tmy
-   iotools.read_pvgis_tmy
-   iotools.get_pvgis_hourly
-   iotools.read_pvgis_hourly
-   iotools.get_pvgis_horizon
+
+
+Commercial datasets
+^^^^^^^^^^^^^^^^^^^
+
+Accessing these APIs typically requires payment.
+
+SolarAnywhere
+*************
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.get_solaranywhere
+   iotools.read_solaranywhere
+
+
+Solcast
+*******
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.get_solcast_tmy
+   iotools.get_solcast_historic
+   iotools.get_solcast_forecast
+   iotools.get_solcast_live
+
+
+Solargis
+********
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.get_solargis
+
+
+Ground station data
+-------------------
+
+Measurements from various networks of irradiance and meteorological
+ground stations.
+
+BSRN
+^^^^
+
+A global network dedicated to high-quality monitoring of solar radiation.
+
+.. autosummary::
+   :toctree: generated/
+
    iotools.get_bsrn
    iotools.read_bsrn
    iotools.parse_bsrn
-   iotools.get_cams
-   iotools.read_cams
-   iotools.parse_cams
+
+
+SOLRAD
+^^^^^^
+
+A solar radiation network in the USA, run by NOAA.
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.read_solrad
+   iotools.get_solrad
+
+
+SURFRAD
+^^^^^^^
+
+A solar radiation network in the USA, run by NOAA.
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.read_surfrad
+
+
+MIDC
+^^^^
+
+A solar radiation network in the USA, run by NREL.
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.read_midc
+   iotools.read_midc_raw_data_from_nrel
+
+
+SRML
+^^^^
+
+A solar radiation network in the northwest USA, run by the University of Oregon.
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.read_srml
+   iotools.get_srml
+
+
+Weather data
+------------
+
+Meteorological datasets from a variety of modeled and measured datasets.
+
+ACIS
+^^^^
+
+A combination of many meteorological datasets providing temperature,
+precipitation, wind speed, and other weather measurements.
+
+.. autosummary::
+   :toctree: generated/
+
    iotools.get_acis_prism
    iotools.get_acis_nrcc
    iotools.get_acis_mpe
    iotools.get_acis_station_data
    iotools.get_acis_available_stations
+
+
+CRN
+^^^
+
+A network of ground stations from NOAA.  Irradiance measurements are of
+relatively lower quality.
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.read_crn
+
+
+Generic data file readers
+-------------------------
+
+Functions for reading local irradiance/weather data files.
+
+.. autosummary::
+   :toctree: generated/
+
+   iotools.read_tmy2
+   iotools.read_tmy3
+   iotools.read_epw
+   iotools.parse_epw
    iotools.read_panond
-   iotools.get_solaranywhere
-   iotools.read_solaranywhere
-   iotools.get_solcast_tmy
-   iotools.get_solcast_historic
-   iotools.get_solcast_forecast
-   iotools.get_solcast_live
-   iotools.get_solargis
 
 
 A :py:class:`~pvlib.location.Location` object may be created from metadata