Import history from a CSV file

For history that is not in weewx or Cumulus format: Weather Display, WeatherCat, a Weather Underground download, a logger export or a spreadsheet. Importing needs Pro or an active trial on the site.

The file is read in your browser, and only the columns you map are sent.

1. Pick the file

Any delimited text file works: comma, semicolon or tab separated, with or without a header row, one row per reading.

In your site's dashboard, open Setup → Connection → Import history and choose the file under From a CSV file. The first rows appear as a preview.

2. Map your columns

Recognised column names (Out Temp, humidity, Barometer, Wind Speed and so on) are mapped for you. Fix any wrong guesses and leave missing measurements on not in file. Only Date / time is required.

3. Check the settings no file states

• Units in the file. Only the units your mapping uses are asked for. A wrong unit puts every value off by a fixed factor.
• Dates are day first (31/12). 03/08/2026 is 3 August in most of the world and 8 March in the United States. A wrong answer silently shifts months, so it is never guessed. ISO dates (2026-08-03) ignore this.
• UTC offset of the timestamps (minutes). Your browser's offset is filled in when you pick the file. Use 0 if the file is in UTC. Timestamps that carry their own zone (ending in Z or +02:00) ignore it.
• Rain column. Choose Running total for the day if the column climbs through the day and resets at midnight, as Cumulus-style exports do. Read as per-reading rain, that would add up to metres. If the column looks like a running total while the setting says otherwise, the import stops and asks; choose Import again to go ahead anyway.
• Overwrite existing readings. Off by default, so readings already stored win and re-running is safe. Switch it on to re-import a corrected file over a bad earlier import: only the columns you map are replaced, and readings you removed in the data editor come back if the file covers them.

4. Import

Choose Import. Progress shows rows sent and rows added; the two differ where your file overlaps readings you already have. Rows with an unreadable date or nothing usable are reported as unusable at the end. Values that convert to something impossible (a temperature of 500 °C) are dropped and the rest of the row is kept.

If the upload is interrupted, run it again. Re-importing the same file adds nothing twice.

What can be imported: temperature, humidity, dew point, wind speed, gust and direction, sea-level and station pressure, rainfall, rain rate, solar radiation, UV index, indoor temperature and humidity, PM2.5 and PM10.