Hi Alex,

You are welcome!

Now that I understand what you meant - let me provide you with a more specific response.

You can check the historical data in any of the previously mentioned EntityClass of weather stations as follows.

For the first 10 stations within EntityClass["WeatherStation", "WMO"], I found data far back to around the 1940s for some of them. Here, I am looking for the monthly mean temperature for the last hundred years.

In[1]:= <|# -> DateListPlot[WeatherData[#, "MeanTemperature", {{1922}, {2022}, "Month"}], 
     Joined -> True]|> & /@ EntityList[EntityClass["WeatherStation", "WMO"]][[1 ;; 10]]

Output:

Also, I would like to mention the Wolfram Data Repository which has various recent and historical meteorological datasets that you may find helpful.

By "longest" I guess you mean with "maximum number of data points". There are a lot of weather stations data in the WL database (~ 35K).

In[1]:= EntityList[EntityClass["WeatherStation", All]] // Length

Out[1]= 35172

However, they are categorized into several EntityClass.

In[2]:= EntityValue["WeatherStation","EntityClasses"]

Out[2]= {EntityClass["WeatherStation", "WMO"], EntityClass["WeatherStation", "CWOP"], EntityClass["WeatherStation", "NCDC"], EntityClass["WeatherStation", "WBAN"], EntityClass["WeatherStation", All]}

Let's take one of that classes with a minimum (seven) number of stations:

In[3]:= EntityList[EntityClass["WeatherStation", "WBAN"]]

Out[3]= {Entity["WeatherStation", "CYUB"],Entity["WeatherStation", "K1H2"],Entity["WeatherStation", "KDTA"], Entity["WeatherStation", "KNAK"], Entity["WeatherStation", "KNFE"],Entity["WeatherStation", "KVKS"], Entity["WeatherStation", "MYEM"]}

We can identify the geographic location of the above stations as follows:

In[4]:= GeoIdentify["Country", #] & /@ GeoPosition /@ EntityList[EntityClass["WeatherStation", "WBAN"]]

Out[4]= {{Entity["Country", "Canada"]}, {Entity["Country", "UnitedStates"]}, {Entity["Country", "UnitedStates"]}, {}, {Entity["Country", "UnitedStates"]}, {Entity["Country", "UnitedStates"]}, {Entity["Country", "Bahamas"]}}

Next, for the temperature data between 1 Aug 2022 and 2 Aug 2022, we use the function AirTemperatureData :

In[5]:= airTemp = Join @@ (<|# -> AirTemperatureData[#, {DateObject[{2022, 8, 1}],DateObject[{2022, 8, 2}]}]|> &/ @ EntityList[EntityClass["WeatherStation", "WBAN"]]) // DeleteMissing

The output of the above In[5] is a list of TimeSeries with the corresponding number of data points.

By creating Association between stations and their data and using DeleteMissing to remove missing data entries, we can visualize the data (available for three) using DateListPlot function:

DateListPlot[airTemp, PlotMarkers -> Automatic, PlotRange -> Automatic, PlotLegends -> Automatic, FrameLabel -> {"Time", "Temperature (°C)"}]

Hence, the weather station (within the specific EntityClass of "WBAN") having the maximum number of data points is K1H2.