UKC

Where is the best place to get weather (temperature) data for the previous few days for a location, for example Kinder Downfall, to check whether the beautiful waterfall will still be flowing. I don't want to walk all the way up there only to find it iced up.

You can get observational data for the past 48 hours on the Met Office website, but of course this will only be for locations with weather stations. Thornecliffe Leek looks to be the nearest, but that is 18 miles away and 330m lower.

https://www.metoffice.gov.uk/weather/observations/gcqxtjw1s

There is also the Met Office WOW site which also includes some unofficial observations (these should be treated with a pinch of salt). Looks like it has some slightly closer, higher obs at Chinely, however, I'm not sure if there is a way of displaying obs more than one hour at a time, so a bit more tricky/tedious to look over a few days.

https://wow.metoffice.gov.uk/

https://www.weatheronline.co.uk/ has historical daily maximum and minimum temperatures going back years, but the number of sites is fairly limited (100 or so across the UK). 

We're scouring the usual places to see if there has even been any hikers up there posting photos. I doubt the downfall will be frozen due to the heat in the sun today but the northern Wildboar fall could be in reasonable condition.

https://holfuy.com/en/map

This site gives you access to weather station data, not sure how much you can get that isn't on the met office website but I find it handy for the CIC hut and various SAIS weather stations. Nothing in the vicinity of kinder though sadly.

ETA: I've wondered from time to time if you can get historical forecast data anywhere but never found anything. The weather forecast for e.g. the next hour is generally pretty accurate, so if you could store the hourly updates from the met office then you'd get a reasonable idea of what the weather has been doing for a given forecast location. Maybe I'll see if I can write some code to try to do this. By 'maybe' what I actually mean is I'll think about it for a few days then do absolutely nothing about it.

A few more useful resources.

Historic weather observations going back at least as far as the 70s, sometimes as far back as the 19th century! https://www.metoffice.gov.uk/research/climate/maps-and-data/historic-statio...

Skylinkweather has more granular data going back a month or so for a number of sites. https://skylinkweather.com/metar/metar-details-time.php

I want to hike all the way up there and find it completly frozen😊

If you want something similar to historical forecast data have a look at the ERA5 dataset. It is basically the result of running an up to date weather forecast model using available observations from 1940 to the present day (latest data is 5 days ago). It’s global in coverage, so relatively coarse resolution over the UK. This means it’s unlikely to capture details related to small-scale height changes etc.

https://climate.copernicus.eu/climate-reanalysis

You can view and download (as a CSV) recent observational data from a wide range of weather stations across the UK - I think wider than the other resources posted so far - at rp5.ru. Search for a location and then go to 'Weather archive at the weather station', which gives data from the nearest weather station.

HadUK daily gridded observational data (https://catalogue.ceda.ac.uk/uuid/4dc8450d889a491ebb20e724debe2dfb) from the UK Met Office are much finer resolution (1km) than the ERA5 product, but less up-to-date.