There are many sources for weather-related data, both paid and free. The National Oceanic and Atmospheric Administration (NOAA) has multiple free datasets available for download. From climatic data to daily averages, there is a lot of useful information to choose from.

The Integrated Surface Global Hourly dataset can be useful for many IoT analytics projects. This dataset includes weather attributes such as air quality, atmospheric pressure, temperature, dew point, wind speed and direction, clouds, and precipitation from over 20,000 global stations. The digital observations are forwarded from various operation centers or decoded directly at the Federal Climate Complex in Asheville, North Carolina, USA.

All the data is stored in a single ASCII format that conforms to Federal Information Processing Standards (FIPS). The data files are sorted by the weather station, year, month, day, hour, and then minute. An example of the dataset is shown in the following screenshot:

The dataset can be downloaded in multiple ways, including with a map viewer. You can also get data definition and other useful documentation from https://data.noaa.gov/dataset/integrated-surface-global-hourly-data.

If you know the latitude and longitude of your IoT devices, you can download the location information for the weather stations from the web page. This information is compiled in a KMZ file. Use this to link to the nearest weather station in order to add the weather attributes at the place and time of IoT data records.