Changelog

Climate Chronicle now contains so many station records and historical measurements, but I was still missing a simple way to analyse this entire dataset across all stations at once. That is exactly what the Data explorer is for.
For any freely chosen period and metric, all stations can be evaluated by maximum, minimum, sum or average and sorted as a ranking list. This quickly shows, for example, which station recorded the highest precipitation, the lowest average temperature or the most summer days in the selected period. The results can also be exported as CSV or PDF.

The climate analysis has been added as a new, extensive view. It processes the existing station data in a spatially balanced way and makes long-term developments visible for each metric and country selection.
In addition to the smoothed 12-month history, the view shows rolling climate trends over 30 and 100 years, historical fluctuation ranges and calculated 50-year continuations. The scenarios are deliberately marked as a mathematical extrapolation, not as a climate forecast.

The chart hints in the station details are clearer: fine dividing lines between date, measurement, means and trend, a slightly translucent background and a grey date.

The current view can be copied and shared via a link button on the map. It includes country, language, metric, date and comparison mode.

Station details have their own link button. The link opens exactly this station, including country and language.

Country, language and an opened station remain visible in the address bar. Such links can be opened and shared directly.

Hola, World Champions! 🇪🇸🏆⚽

Spain is now part of Climate Chronicle. The historical monthly data come from the Spanish weather service AEMET. Retrieval runs station by station via the open data interface, with a little over 900 stations.

Station charts now show 10- and 30-year means instead of 36 months. The 30-year line appears in the legend only on wider screens.

The mean lines no longer start with a sudden rise when too few months are available at the beginning. A point only appears once the complete time window is available. More detailed information on the calculation is on the measurements page under Calculations.

Place names now remain stably positioned when the map is moved and fade out slightly when a place and station point overlap.

The map screenshot includes the green line representing the number of stations on the timeline. If required, the screenshot can also be output without the trend line and station count if this feature was previously disabled.

Cześć, Polsko! 🇵🇱

Poland is now available as another country in Climate Chronicle. Integrating the Polish climate data was, to put it simply, exciting. Formats, workflows and processing needed substantial extra work and many new adjustments before they could be integrated reliably. For Poland, daily data are now also converted. In the end, everything worked. A warm welcome, Poland! 🇵🇱

Ahoj, Česko! 🇨🇿

The integration went well overall. The language barrier was once again a bit tricky, and the station IDs also needed some thought - more on that later in the data diary.

Due to the current issues with the Polish data, I decided that an integration diary for each country would make sense. The experience and data gained from this might also be interesting for others.

The measurements page now explains data sources, data gaps and the calculation of monthly values from daily data.

The calculation overview is now available in German and English and explains the rule for complete months.

Climate data downloader updated for Czechia and Poland.

The charts now also show the number of stations.

The climate data mapper can now calculate monthly values from daily values. The current description of the calculation can be found here.

The climate data mapper now shows mappings, warnings and the export result more clearly.

The downloader now logs progress and possible issues when retrieving data in far greater detail.

The previous individual download tools have been merged into one new shared downloader.

Start links can now select the language and one or more countries directly, for example ?countries=AT,DE&lang=en.

Bonjour France 🇫🇷 - now officially active as a country.

And wow … do they have stations. More than 10,000 stations marked the first time my site briefly buckled under the load. 😄 A fantastic challenge and, at the same time, a good reason to rethink quite a few things under the hood.

France also makes its data available in an absolutely exemplary way: comprehensive, structured and highly usable. The only minor stumbling block was that many of the relevant pages have little or no English translation, so translation tools became a constant companion during the integration.

In terms of connecting the data alone, France could probably have been integrated as quickly as Switzerland. However, the enormous volume of data meant that I had to simplify and optimise several things in parallel. After all, I have to expect more countries with data volumes like these to follow, and next time I want to be prepared.

All in all: a genuinely exciting challenge, extremely educational from a technical perspective, and once again great credit for how openly and exemplarily the data is provided. 🇫🇷

Added extended precipitation values for Switzerland (Ah, so that is where the other stations were hiding :D)

Added extended precipitation values for Germany.

JSON data now includes a data version identifier so that current data is always loaded independently of old browser caches.

Almost 30,000 JSON files are now packaged, uploaded and unpacked on the server in under five minutes.
The files are deliberately stored uncompressed in an archive, which saves time, and are then unpacked directly on the server via SSH. With this number of files, a complete upload was much faster than checking every individual file by hash beforehand, and I am now very happy with the speed.

The measurement data page now shows a sortable overview of data availability by country and metric, including the latest data status, station counts and sources derived from the source data, so these values are always up to date.

If MapTiler is unavailable or its usage limit has been reached, OpenStreetMap now takes over automatically.
I designed the MapTiler map myself over several days to give it a slightly historical look, and I quite like the result. Unfortunately, MapTiler becomes fairly expensive quite quickly as usage increases. As a precaution, there is therefore a fallback: as soon as the relevant limits are reached, OpenStreetMap takes over automatically.

Not quite as pretty - but MapTiler for the eyes and OSM for the bank balance. 😄

The map legend now displays the six metric colours as a continuous gradient, and I think I will need to expand the palette soon. In view of the new heat records, six colours seem to normalise values around 30° too strongly.

Station labels and hover tooltips can now use a custom colour for each metric and country.

The current map view can now be exported as an A4 PNG. The export retains the map extent and visible layers and adds the timeline, data overview and source information.

The heatmap now updates more smoothly after the map is moved and is rendered more efficiently internally - fewer stressed pixels, same message.

A multi-stage loading indicator shows the current progress when the home page opens.

The loading indicators for station details and PDF export now show several clear processing stages.

The loading indicator now closes reliably even when an error occurs and no longer blocks the page.

Station details can be transferred directly to the comparison and now show the available data period.

PDF reports now have a compact footer with station details, creation date and page number.

Charts are no longer split across two pages during PDF export.

The timeline now responds more smoothly when dragged and shows the selected month more clearly.

The currently selected period is now also shown directly above the timeline.

Weather stations now make it easier to see the periods for which data is available.

Station details have a clearer structure so important information can be found more quickly.

Some stations without current values were not always displayed correctly. This has been fixed.

Empty measurements no longer cause the curve to continue at an incorrect position.

Grüezi Switzerland 🇨🇭 - now active as a country. It is a little unfortunate that comparatively few stations are currently in use. All the more, I would like to highlight how exemplary Switzerland makes its data available: clean, accessible and straightforward. This made complete integration possible in just two days. That is how data integration becomes fun. 🇨🇭

The large timeline now shows a linear trend that can be toggled on and off once enough stations are available.

Country and metric changes now show a loading notice directly on the map during longer updates.

The map preloads data for adjacent views in the background, making it feel faster.

When changing metrics quickly, the map was sometimes updated too late. It now shows the correct values immediately.

The heatmap circles now have softer, clearer edges without an additional blur filter.

Austria is framed more closely and centred on the map when loading.

The "All" button now takes its name seriously and disables all countries with one click - previously it could only enable them all ;D.

Place names on the map now adapt better to the selected language and map extent.

Additional place names now make familiar regions easier to identify on the map.

Labels overlap much less frequently on smaller map views.

Place names no longer disappear unexpectedly when zooming in or out.

The map now stops immediately when released instead of taking a small victory lap - saving even more processing power.

The update interval, precomputed map margin and vector-map reloading have been optimised for smoother rendering.

The vector map now moves more smoothly while being dragged because expensive map updates, including the heatmap, pause during movement and run once afterwards. I know this looks a little unusual, especially with the heatmap, but it is the only way to keep the map smooth when several large countries are active.

Old station points no longer remain on the map when switching between countries.

Large numbers of stations are now selectively aggregated on the map and in the heatmap depending on the zoom level.

Station markers are now created only within the visible map extent, rendered in reduced detail when zoomed out and updated efficiently as the map moves.

Station search now finds matching places more reliably even when the input is incomplete.

The station list can now be filtered by country and available data.

The distance to a station is now recalculated correctly after a new map selection.

Two weather stations can now be compared directly.

Differences between two stations are now explained more clearly in the comparison.

The comparison view now once again adopts the selected period correctly.

Two periods of equal length can now also be compared.

Comparison results are now summarised more compactly.

Months with missing data are no longer incorrectly included in comparisons.

Automatic playback now preloads target dates to keep the journey through time running smoothly and displays suitable tooltips.

Map colour gradients now make small and large differences in measurements more visible.

All help texts now use a consistent numbered layout with clearly separated sections.

Explanations for the map and the large timeline have been added in German and English.

The map can now show two points in time side by side, making changes easier to identify.

The slider between the two map views can now be controlled more precisely.

The split map view remains correctly aligned after the window is resized.

Unavailable metrics are now hidden for the selected countries and point in time.

The base map can now be hidden, leaving the map with a solid-colour background. If you are going to watch climate change in fast-forward, you can at least give it a stage so that it finally receives the visual focus it has been asking for over the past few decades ;).

Month selection no longer overshoots at the beginning or end of the available period.

Month selection now shows more clearly which months can be selected.

The map and main timelines can now play forwards and backwards automatically in monthly, yearly, five-year or ten-year steps. Not strictly necessary, but it simply looks damn cool. So it had to go in. 😄

Information about measurements is now easier to understand and dismiss.

Important settings now have short explanations in a modal dialog.

The explanations now work better with keyboard controls.

Open notices can now be closed reliably even after changing views.

A help icon in the reference selector now explains that the calendar month is taken from point B.

In the monthly comparison within station details, month and year are now selected separately for points A and B, instead of sausage.

Individual stations now have clear charts for temperature, precipitation and other measurements.

Comparison sides A and B now each show their own station markers and simple tooltips matching their data.

The most important settings are once again accessible on small screens without excessive scrolling.

The map view now adapts better to smartphones and smaller tablets.

Buttons have more spacing and are therefore easier to tap.

Measurement data from Germany and Austria is now displayed together.

The most important measurements are explained on the map using clear colours and a simple legend.

The map comparison can now compare a fixed climatological reference period with a freely selected point B.

A new tool now generates reference files for all metrics with minimum monthly coverage and two decimal places.

The HadCRUT5 comparison now explains local and global temperature anomalies more clearly through its tooltips.

Lines, difference areas and the legend in the HadCRUT5 chart now have a clearer colour scheme, and the tooltip is much tidier (yes, it really was even more cumbersome before ;D).

Hashed CSS and JavaScript files can now be cached in the browser for the long term.

A new tool now prepares files for automated uploads.

Vite now bundles and minifies my CSS, which as usual had grown too large, and all the JavaScript files.

Mobile tooltips for monthly trends and HadCRUT5 now remain stable, compact and within the visible area.

The station-detail dialog no longer wanders sideways on mobile devices; its fixed header remains above the help buttons while scrolling.

Station selection and station charts now use mobile space more efficiently, and legends no longer overlap the charts.

Month selection in station details is now limited to the station's available period.

Comparison charts now show comparison A in blue and comparison B in red; two monthly values are displayed as separate bars.

File names for PDF and CSV exports are now generated according to the selected language.

When a country is activated for the first time, the country filter briefly shows a spinner so nobody thinks the page has clocked off.

Station markers are now created in batches and reused when switching countries.

The home page initially loads only the active country; additional countries are added only when needed and prepared in the background.

Static files are now compressed and cached in the browser so that subsequent page visits load faster.