Every file here is made-up UK weather, free to use for anything under CC0. The files run from a few rows to 100,000 to download, or 1 million made in your browser. Plot it online opens a file in your browser, Download saves a copy, and there is nothing to sign up for.
| To try | Sample | Format |
|---|---|---|
| A line chart | Cardiff daily temperature | CSV |
| A bar chart | Glasgow monthly rainfall | CSV |
| A scatter plot | Belfast temperature and humidity | CSV |
| A time series | Leeds hourly weather, one year | CSV |
| A big file | UK hourly weather, 100,000 or 1,000,000 rows | CSV |
| An Excel workbook | UK weather workbook | Excel |
| A MATLAB .mat file | UK weather Simulink simulation | MATLAB |
| A LabVIEW TDMS file | UK weather, one month | TDMS |
| An HDF5 file | UK weather, one month | HDF5 |
| A Parquet file | UK hourly weather, ten years | Parquet |
Three small files, each made for one kind of chart. Each has a header row and a units row under it, and Plot it online opens it as that chart.
CSV · 365 rows × 3 columns · 7.39 KB
The highest and lowest temperature of every day of 2025 in Cardiff, in °C: a year as a line chart.
Columns: date, Cardiff_Temperature_Max (°C), Cardiff_Temperature_Min (°C)
| date | Cardiff_Temperature_Max | Cardiff_Temperature_Min |
|---|---|---|
| 2025-01-01 | 9.0 | 3.2 |
| 2025-01-02 | 8.7 | 3.1 |
| 2025-01-03 | 6.2 | -1.0 |
| 2025-01-04 | 5.5 | -2.1 |
| 2025-01-05 | 6.6 | -0.8 |
CSV · 24 rows × 3 columns · 477 B
The rainfall in mm and the days with rain of every month from January 2024 to December 2025, the months written as Jan 2025: a bar chart.
Columns: month, Glasgow_Rainfall (mm), Glasgow_Rain_Days (days)
| month | Glasgow_Rainfall | Glasgow_Rain_Days |
|---|---|---|
| Jan 2024 | 160.6 | 22 |
| Feb 2024 | 143.6 | 20 |
| Mar 2024 | 95.0 | 14 |
| Apr 2024 | 62.7 | 11 |
| May 2024 | 94.6 | 14 |
CSV · 365 rows × 3 columns · 9.04 KB
One reading at 15:00 on every day of 2025 in Belfast, the temperature in °C and the relative humidity in %, the rows ordered from the coldest afternoon to the warmest. Plotted against each other as a scatter, the warmer afternoons are the drier ones.
Columns: time, Belfast_Temperature (°C), Belfast_Humidity (%)
| time | Belfast_Temperature | Belfast_Humidity |
|---|---|---|
| 2025-02-04 15:00 | 3.5 | 98 |
| 2025-02-03 15:00 | 4.1 | 98 |
| 2025-01-28 15:00 | 4.3 | 91 |
| 2025-02-07 15:00 | 4.6 | 89 |
| 2025-01-02 15:00 | 4.8 | 97 |
Hourly readings in three sizes, for trying a tool on a long file. The plotter’s speed figures, and how they are measured, are in how we measure speed.
CSV · 8,760 rows × 5 columns · 299 KB
Every hour of 2025 in Leeds: temperature, humidity, wind speed and rainfall.
Columns: time, Leeds_Temperature (°C), Leeds_Humidity (%), Leeds_Wind_Speed (mph), Leeds_Rainfall (mm)
CSV · 100,000 rows × 8 columns · 4.69 MB
The last 100,000 hours of the 1,000,000-row sample, from September 2014 to January 2026: four city temperatures, Belfast’s humidity, Glasgow’s rainfall and Aberdeen’s wind speed.
Columns: time, London_Temperature (°C), Manchester_Temperature (°C), Edinburgh_Temperature (°C), Cardiff_Temperature (°C), Belfast_Humidity (%), Glasgow_Rainfall (mm), Aberdeen_Wind_Speed (mph)
CSV · 1,000,000 rows × 8 columns · 46.7 MB when made
One reading an hour from 1912 to January 2026, in the same eight columns, with nothing to download.
Made in your browser (46.7 MB). To save it: Do more → Download all columns (CSV).
| time | London_Temperature | Manchester_Temperature | Edinburgh_Temperature | Cardiff_Temperature | Belfast_Humidity | Glasgow_Rainfall | Aberdeen_Wind_Speed |
|---|---|---|---|---|---|---|---|
| 2014-09-02 00:00 | 11.7 | 9.7 | 9.2 | 12.4 | 85 | 0.0 | 3.5 |
| 2014-09-02 01:00 | 11.6 | 9.7 | 9.4 | 12.5 | 92 | 0.0 | 5.8 |
| 2014-09-02 02:00 | 12.0 | 9.5 | 9.2 | 12.7 | 90 | 0.0 | 2.2 |
| 2014-09-02 03:00 | 11.7 | 9.5 | 9.2 | 12.3 | 91 | 0.0 | 2.4 |
| 2014-09-02 04:00 | 12.8 | 10.7 | 9.8 | 12.8 | 96 | 0.0 | 0.9 |
Excel · 3 sheets · 6.33 KB
An .xlsx workbook of three sheets, with dates, formulas saved with their results, and a percentage column.
| Sheet | Rows | Columns | What is in it |
|---|---|---|---|
| Daily | 31 | 8 | January 2025 in London: the highest, lowest and mean temperature (the mean a formula), humidity as a percentage, rainfall, frost and the weather in words |
| Monthly | 12 | 5 | the rainfall of London, Leeds and Glasgow in each month of 2025, with the total as a SUM formula |
| Stations | 5 | 6 | five weather stations with their positions, heights, the date each record starts and the last update |
Your own files: convert a sheet to CSV.
MATLAB · MAT-file v7 · 52.3 KB
A Simulink simulation of made-up UK weather, saved by MATLAB as a v7 MAT-file: its SimulationOutput with a logged Dataset (signals at 0.1 s, 0.5 s and 1 s, and a bus of two), the outputs and states, and To Workspace variables in four formats.
Your own files: MAT file viewer · MAT to CSV.
TDMS · 3 groups · 105 KB
A month of made-up UK weather from January 2026 in three groups, each at its own rate, with waveform timing and channel properties such as unit_string and description.
| Group | Rows | Columns | What is in it |
|---|---|---|---|
| Hourly | 744 | 5 | temperatures in London, Leeds and York, London’s humidity and pressure, every hour from 1 January 2026 |
| Rain gauge | 4,464 | 2 | rain in London and Leeds every ten minutes, on its own time base |
| Daily | 31 | 4 | a timestamp channel, Date, which becomes the time axis, the day’s highest and lowest temperature and the weather in words |
Your own files: TDMS viewer · TDMS to CSV.
HDF5 · 4 tables · 74.4 KB
The same month as the TDMS file, written with h5py: three groups at three rates, each with its own time, units as attributes, and a 2-D dataset.
| Table | Rows | Columns | What is in it |
|---|---|---|---|
| /hourly | 744 | 5 | temperatures in London, Leeds and York, London’s humidity, and its pressure stored packed, every hour from 1 January 2026 |
| /rain_gauge | 4,464 | 2 | rain in London and Leeds every ten minutes, on a time of its own |
| /daily | 31 | 4 | the day’s highest and lowest temperature, its rain and the weather in words |
| /stations/wind_speed | 744 | 4 | one 2-D dataset of 744 hours × 4 stations: a column per station, named by its station dimension, against the hourly time |
Your own files: HDF5 viewer · HDF5 to CSV.
Parquet · 87,672 rows × 20 columns · 2.38 MB
Ten years of made-up hourly UK weather in 20 columns of mixed types, one row group per year.
Your own files: Parquet viewer · Parquet to CSV.
| File | Size | SHA-256 |
|---|---|---|
| megarows-sample-cardiff-daily-temperature.csv | 7.39 KB | 4223d5dfa54f73032eab37f29d432a2fe414fc08cfc752ec9a2d9e2981c4f7c4 |
| megarows-sample-glasgow-monthly-rainfall.csv | 477 B | 780b601225b455e76a9eb57150f3f9a54d4b2c56ae3863355659ec3e6548fc9f |
| megarows-sample-belfast-temperature-humidity.csv | 9.04 KB | 850d429162e781b8af73edd19b4b0bf5ec73b152f3ba2838ba38178b8dd10acb |
| megarows-sample-leeds-hourly-weather.csv | 299 KB | 1caa85c18093655fb71fd20ff06788b77a0f0b07bf9309d5dd9999ca4cbcd855 |
| megarows-sample-uk-hourly-weather-100k.csv | 4.69 MB | 8f6672e004d4f82042b89370253e7997525a40b82855a21bb61555df863c766e |
| megarows-sample-uk-weather-stations.xlsx | 6.33 KB | a0147b0d396298b2b775cd6edd70bdea16a6bc31349ceca1ee2c83ddfaf7de53 |
| megarows-sample-uk-weather-simulation.mat | 52.3 KB | 35ba21cfc573dfd48debea656a1328c5db7636ff971a9cb579de907631e2d12a |
| megarows-sample-uk-weather.tdms | 105 KB | abcd87b78569db6f547ce43d54180a14ceb8c4111726139057491cd4dce1644b |
| megarows-sample-uk-weather.h5 | 74.4 KB | a0a02792d2a02548d9c5611f465b0d0bb0296d2b96bbbf4fc2b88d241f221937 |
| megarows-sample-uk-weather.parquet | 2.38 MB | 9c4040e8364099ccea4c5d507a984d9da536b8622c7a233629d57d1d3e51eef1 |
No. Every value is made up, by a program or a Simulink simulation, and named after UK cities so the files read like real measurements. None of them holds data from a real weather station.
Yes. They are free to use for anything, also commercially, without asking or naming MegaRows: they are dedicated to the public domain under CC0 1.0. Copy them into your own repository, tests or course material.
Choose Plot it online next to the file: the MAT file opens in the MAT file viewer and the TDMS file in the plotter, in your browser, with nothing to install. Your own .mat and .tdms files open there the same way, and they stay on your device.
Cardiff daily temperature for a line chart, Glasgow monthly rainfall for a bar chart, and Belfast temperature and humidity for a scatter plot. Plot it online opens each one as that chart, and the same three are the examples under the CSV plotter.
Choose Make and plot 1,000,000 rows: the plotter makes the file in your browser (46.7 MB) and plots it, with nothing to download first. To save it as a CSV, choose Do more → Download all columns (CSV). The biggest file to download is the 100,000-row one (4.69 MB).
Yes. Each of the three starts with a header row of column names, such as Cardiff_Temperature_Max, and a units row under it with each unit in square brackets: [°C], [mm], [days] and [%]. The plotter reads that row as units, not as data.
Yes: ten years of made-up hourly UK weather, 87,672 rows × 20 columns of mixed types, 2.38 MB, with one row group per year. Plot it online opens it in the Parquet viewer, and Download saves a copy.
No. There is no account and nothing to sign up for: Download saves a file straight away, and Plot it online opens it in your browser.
Plot it online opens each file in your browser, on your device. Your own files open there the same way, and nothing is uploaded.