This list is (and may always be) incomplete. Please add to it when you can.
NOAA's ISD data (goes back to ~1900 in some cases):
https://www.ncdc.noaa.gov/isd (home page)
ftp://ftp.ncdc.noaa.gov/pub/data/noaa/ (direct link to data, some stations include multiple report per hour in some cases)
https://www1.ncdc.noaa.gov/pub/data/noaa/isd-lite/ (direct link ...
Get the data from BigQuery:
SELECT name, stn, a.wban, TIMESTAMP(CONCAT(year, '-', mo, '-', da)) date, temp, prcp
FROM `bigquery-public-data.noaa_gsod.gsod2*` a
AND name LIKE '%...
A remodel of weather since 1979, based on many many measurements. The resulting dataset contains daily to hourly values around the globe for many meteorological and climatological parameters such as temperatures, water content, wind, radiation and various fluxes.
The most up to date version of ...
The World Glacier Monitoring Service
The World Glacier Monitoring Service hosts database with mainly mass balance, front variation and thickness change data. The main website is:
http://wgms.ch/ the map with data can be found here: http://www.wgms.ch/metadatabrowser.html
The Global Land Ice Measurements from Space initiative hosts another ...
There's a good list of weather data sources on this excellent website created by Robin Wilson, which I duplicate here in case that site ever goes away:
WorldClim: Climate data for past, present and predicted future conditions. Includes temperature (min, max, mean) and precipitation. 1km x 1km resolution.
NCAR GIS Climate Change Scenarios: Lots of data from ...
I recently found this website for downloading weather data: https://rp5.ru/ which is the website of Reliable Prognosis, a company from St-Petersburg. The website is mainly dedicated to weather forecast, but you can find historical weather data (weather archive). There are interesting features for historical weather data:
Available data from "8400 SYNOP ...
For generic corrosive properties, this is a typical question for a scientific and engineering reference book, like the CRC Handbook (check your local library)
But for specific materials, these will come from the manufacturers. Try searching "corrosion tables" with some other keywords, until you find the one that works. Here are some examples:
European data can be obtained from ECMWF at http://apps.ecmwf.int/datasets/data/interim-full-daily/levtype=sfc/ and they have an API https://software.ecmwf.int/wiki/display/WEBAPI/Python+ERA-interim+examples
If you're looking specifically for a small region in the European interior, you're going to need model simulations at the regional scale. For that I'd suggest checking out the CCAFS Downscaled Climate Change data portal: http://www.ccafs-climate.org/data/
The data offered there are 30-year monthly normalizations of most every AR4 and AR5 climate models and ...
The European Centre for Medium Range Weather Forecasts hosts a database with this information here: http://apps.ecmwf.int/datasets/data/interim-full-daily/levtype=sfc/
They require you to create an account (free) before you can request data. The data is available per lat/lon grid point, so you'll have to look up which grid points are within which country.
Running list of UV/UVI/Air Quality/AQI data sources:
Ultraviolet Index issued by NWS
World Ozone and Ultraviolet Radiation Data Centre (WOUDC)
Solar Ultraviolet Spectral Irradiance
Solar Data Services
Solar UV Index
Stratosphere: UV Index
Global Fields of UV Index Forecasts
USDA/Colorado State Univ UV-B Monitoring and Research Program
NOAA SURFRAD - ...
Finally I found some useful links for station-based data for period 1981-2010:
data for Austria:
data for Germany:
data for switzerland:
The Atmospheric Radiation Measurement (ARM) program has been collecting precipitation, temperature and more for decades. You’ll want other datasets to get global coverage, but ARM data will give you a high level of detail and quality for the areas they cover.
ARM focuses on obtaining continuous measurements—supplemented by field campaigns—and providing ...
Based on BarryCarter's comment
Integrated Surface Database (ISD) from the National Climatic Data Center (NCDC)
The Integrated Surface Database (ISD) consists of global hourly and synoptic observations compiled from numerous sources into a single common ASCII format and common data model.
And the data