Datum Weather · Getting started
You've been invited to the Datum beta. This walks you from the invitation email to a working forecast — about five minutes, and you only need a Weather Underground key if you own a weather station.
Open the invitation email from Datum Weather and follow the link to choose a password. The link signs you in once — after that you'll use your email address and the password you just set.
No email? Check spam and promotions first. If it still isn't there, reply to whoever invited you and ask them to re-send it — invitations can be issued again without losing your place.
Signing in for the first time opens a single question: Where should we forecast for? There are two ways to answer it, and the right one depends only on whether you own a weather station.
Uses your own instrument as the ground truth your forecasts are measured against. You'll need a Station ID and an API key — see step 3.
Type a town, postcode or place into Town, postcode or place, press Search, and pick your spot from the results. Nothing else is needed — skip straight to step 4.
Either route gets you a working forecast today, but they aren't equivalent. A station at your location measures your weather where you actually are. An address is scored against the nearest instruments we can reach, which may be miles away and at a different elevation — and that distance shows up in the grade. If you have a station, use it. If you don't, start with the address and add one later.
Weather Underground issues API keys to people who contribute data from a personal weather station. If your station is already registered and uploading, your key exists — you just need to go and read it.
KTNSUMME12.Back in Datum, put the Station ID in Station ID and the key in Weather Underground API key, then press Look up my station. Datum reads your station's current observation to find its position and elevation, so there's nothing else to type.
No station registered yet? Weather Underground only issues API keys to station owners, so there's no key to find until a device is registered and uploading. Use Use my address instead today and add the station once it's live.
Datum shows you a pin on a map and asks Is this the right spot? Check it, then press Yes — set up my account. If it's wrong, press Back and search again.
You'll see You're set up. and then a choice of apps. Pick one and your dashboard opens.
Your first forecast appears immediately. Accuracy scores build up over the following days, as Datum compares each forecast against what was actually measured — so a new account shows forecasts right away and grades a little later.
If something goes wrong
Datum tells the three station failures apart, so the message you get points at the fix.
| What you see | What it means | What to do |
|---|---|---|
| Key rejected | Weather Underground didn't recognise the key. | Re-copy it from the API Keys page — all 32 characters, no spaces at either end. |
| Station idle | The key works, but your station hasn't reported recently. | Check the station is powered and uploading, then try again. Datum needs a current reading to find its position. |
| Can't reach Weather Underground | Their service didn't answer. | Nothing is wrong on your side. Wait a few minutes and press Look up my station again. |
| Address not found | The search didn't match a place. | Try a nearby larger town, or add the state or country —
Summertown, TN rather than Summertown. |
Setup is safe to repeat. If anything fails partway, nothing is saved — sign in again and you'll be back at Where should we forecast for?
Good to know
It's stored encrypted and tied to your account. Datum never shows it back to you in full — if you look at your settings later you'll see only the last few characters, which is enough to tell one key from another and not enough to use it.
Datum grades its own forecasts. Every prediction is checked afterwards against what was actually measured, and the score you see is the result — so the grade is only ever as good as the instrument behind it. A station you own measures your weather where you actually are. An address is scored against the nearest instruments we can reach: useful, and honest about being a stand-in, but they can sit miles away and hundreds of feet higher or lower than you. That's the whole reason to connect a station if you have one.