Why Your Weather Station Needs Automatic Data Backup

Weather data has a quality that makes it different from most other digital information: it is irreplaceable. If you lose a photo, you might have another copy. If you lose a document, you can recreate it. But if you lose last year's rainfall totals, the highest wind gust of the season, or the temperature record from that heatwave, that data is gone forever. You cannot re-measure past weather.

Despite this, most personal weather station owners have no real backup strategy. Their entire history lives on a single SD card in a Raspberry Pi or in the limited retention window of the WeatherLink free plan. This post explains the risks and how to fix them.

Where is your weather station data stored right now?

Where your data lives depends on how you run your station: on the WeatherLink free plan, long-term history is limited; on WeatherLink Pro or Pro+, it is stored on Davis's servers; with CumulusMX or WeeWX, it sits on a Raspberry Pi's SD card or USB drive — a single point of failure in your house.

In more detail:

• WeatherLink free plan. Your current conditions are visible, but historical data is limited. Older observations roll off over time, and the free tier does not expose historic data through the API. If you rely solely on WeatherLink Basic, you do not have a long-term archive at all.
• WeatherLink Pro or Pro+. Your data is stored on Davis's servers, which is more reliable than a home setup. But you are paying extra for it, and it is tied to the WeatherLink ecosystem and its fixed interface.
• CumulusMX or WeeWX on a Raspberry Pi. Your data lives on the Pi's SD card or a USB drive. SD cards are notorious for corruption, especially under continuous write loads. If that card fails, your entire history can vanish.
• Manual backups. Some owners periodically copy their data directory to an external drive or cloud storage. This works but depends on remembering to do it, and most people forget until it is too late.

Why do self-hosted weather setups lose data?

Self-hosted setups lose data because one device does everything: it collects the observations, stores the database, and generates the website. When that device fails, there is no second copy anywhere else, so the entire history goes with it. That is three eggs in one basket, sitting in your house.

Common failure scenarios:

• SD card corruption. The most common Raspberry Pi failure. Continuous logging wears out SD cards faster than typical desktop use.
• Power outage with filesystem damage. An unclean shutdown can corrupt the weather database.
• Fire, flood, or theft. If your home has an incident, the Pi goes with it.
• Quiet database corruption. Sometimes a database file becomes corrupted gradually. By the time you notice, the backups you do not have cannot help.

What does a good weather data backup strategy look like?

A good backup for weather data is automatic, off-site, and versioned: it runs on a schedule without you thinking about it, it stores copies somewhere other than your house, and it keeps dated snapshots rather than overwriting a single copy — so corruption discovered late can still be rolled back.

In practice, that means three properties:

1. Automatic. It runs without you thinking about it.
2. Off-site. It stores a copy somewhere other than your house.
3. Versioned. It keeps historical snapshots, not just the latest copy.

If you self-host, you can achieve all three with a script that periodically copies your weather data to a cloud service like Backblaze B2 or AWS S3, or a simple rsync to a remote server. This works well once set up — but it is yet another system to build, test, and maintain, and a backup that has never been test-restored is a hope, not a plan. Put a periodic restore test on your seasonal routine alongside sensor cleaning; the weather station maintenance checklist is a good place to anchor it.

What is the easiest way to keep weather data safe?

The easiest way is to use a hosted service that stores your data off-site as part of its normal operation. Pro Weather writes every reading from your station to its database as the data arrives and keeps your full history indefinitely, with no separate backup for you to configure.

Pro Weather stores every reading server-side, indefinitely, as part of your subscription. Your data is written to the database every 10 minutes and is replicated as part of the hosting infrastructure. If your house loses power, your Raspberry Pi fails, or your SD card corrupts, your complete history remains intact and accessible on your site.

This is what you are paying for when you subscribe: not just the website, but the assurance that your data is not going to disappear.

What should you do today?

Look at where your weather data lives right now. If the answer is "on an SD card" or "only on the WeatherLink free plan," your history is at risk. The fix is either to set up automatic off-site backups or to move to a hosted service that handles storage for you.

For a comparison of the software options, see Best Weather Station Software for a Personal Website. If you want automatic data retention without managing backups, start your Pro Weather site and your data will be stored from day one.

Common questions

How do I back up WeeWX data?

WeeWX stores its archive in a SQLite database by default (weewx.sdb). The simplest safe method is to stop WeeWX, copy the file, and restart — or use SQLite's online .backup command to copy the database while WeeWX keeps running. Automate that copy with a nightly cron job plus rsync or a cloud sync tool, so a dated snapshot leaves the house every day.

How do I back up CumulusMX data?

CumulusMX keeps its history as plain files in its data folder (the day file and monthly logs) and writes its own daily backups to a local backup folder. Copy both folders off the machine on a schedule — a nightly script syncing them to cloud storage or another computer is enough. A backup that stays on the same SD card protects you from nothing.

Does WeatherLink keep my history forever?

That depends on your plan. WeatherLink's cloud stores what your station uploads, but access is plan-dependent: the free Basic tier shows current conditions and does not expose historic data through the API, while Pro and Pro+ unlock the historic archive at finer intervals. WeatherLink Basic vs Pro vs Pro+ breaks down exactly what each tier includes.

How often should weather data be backed up?

Nightly is the sensible default: weather data accrues continuously, so a daily automated backup means you never lose more than a day of history. What matters more than frequency is that the backup is automatic and off-site — a weekly copy that actually runs beats a daily one you have to remember. Keep several dated snapshots so corruption discovered late can still be rolled back to a clean copy.