Direct API request inaccurate about current weather, but Merry Sky is accurate

[jeremysalwen]

Describe the bug

It has been raining for the last few hours. The HA integration has been saying the precipitation intensity is zero the whole time. Directly querying the API shows zero intensity as well.

https://api.pirateweather.net/forecast/APIKEY/43.847,-72.541,1746167070?units=us

However, Merry Sky has no problem identifying that it has been raining for hours and will continue to do so:

(other forecasts also have this information correct)

Expected behavior

1. Accurate current weather conditions
2. Failing that, current weather conditions that match what Merry Sky Give

Actual behavior

API Endpoint

Production

Location

South Royalton, Vermont

Other details

I have seen other reports of this sort of bug, but nothing that is applicable to my specific symptoms.

Troubleshooting steps

• I have searched this repository and Home Assistant Repository to see if the issue has already been reported.
• I have read through the API documentation before opening this issue.
• I have not included my API key anywhere in my issue.
• I have written an informative title.

[cloneofghosts]

While I'm not 100% on how Merry Sky works it appears that the current conditions shown is the current hour hourly forecast which would explain the differences you are seeing.

As for the precipitation issue there's a few things going on:

1. Precipitation Rates below 0.36 mm/hr don't appear in the model data (see: currently block often struggles with precipitation #390 (comment))
2. Pirate Weather uses near-realtime model data so it's possible that due to the delay it hasn't shown any rain yet.

There are some plans in the future to help mitigate this issue being switching to reflectivity products for precipitation and adding in realtime weather models (RTMA and 3DRTMA when it launches).

Will ping @alexander0042 as well in case he has anything else to add.

[jeremysalwen]

I don't think the 0.36 mm/hr limit is directly responsible for the bad outcome here. The actual amount of accumulation recorded by a weather station less than 1 mile away is 6.3mm over 4 hours, which gives an average rate of 1.6mm/hr, nowhere near 0.36 mm/hr. And the peak rate was 12.7mm/hr!

Even the Merry Sky forecast reaches double the 0.36mm/hr limit in the screenshot provided.

I also checked other weather stations in a 15 mile radius, every single one recorded at least 4mm of rain total, and some up to 12mm. I'm not sure how this could translate into no precipitation at any time during the night unless there is a bug.

[cloneofghosts]

I don't think the 0.36 mm/hr limit is directly responsible for the bad outcome here. The actual amount of accumulation recorded by a weather station less than 1 mile away is 6.3mm over 4 hours, which gives an average rate of 1.6mm/hr, nowhere near 0.36 mm/hr. And the peak rate was 12.7mm/hr!

I also checked other weather stations in a 15 mile radius, every single one recorded at least 4mm of rain total, and some up to 12mm. I'm not sure how this could translate into no precipitation at any time during the night unless there is a bug.

I'll ping @alexander0042 since he would be able to dig into the data and see what exactly happened. The currently data shown in the API largely comes from a different model then what the hourly data comes from (see https://pirateweather.net/en/latest/DataSources/#forecast-element-sources for a detailed explanation).

The reason why Merry Sky showed rain as the current condition and the API didn't is because Merry Sky doesn't pull any data from the currently data block as the current conditions. It is actually pulling in data from the first hour in the hourly data section.

I queried your location and Merry Sky is showing:

If I take a look at the API (in this case briefsky) it shows:

The first hour data is as follows:

{
  "time": 1746212400,
  "summary": "Possible Drizzle",
  "icon": "partly-cloudy-day",
  "precipIntensity": 0.254,
  "precipProbability": 0.11,
  "precipIntensityError": 0.0699,
  "precipAccumulation": 0.0254,
  "precipType": "rain",
  "temperature": 20.16,
  "apparentTemperature": 18.98,
  "dewPoint": 13.41,
  "humidity": 0.66,
  "pressure": 1008.64,
  "windSpeed": 11.88,
  "windGust": 22.32,
  "windBearing": 230,
  "cloudCover": 0.47,
  "uvIndex": 3.94,
  "visibility": 16.09,
  "ozone": 323.12
},

If you take a look the data I posted matches almost exactly what Merry Sky is showing in my screenshot.

It could be that the variable that Pirate Weather is pulling from didn't reach the 0.36mm/h threshold whereas if you look at radar products it would have shown rain. There are plans to change to using radar products instead of using the precipitation rate variable which should improve things but no ETA on that.

[jeremysalwen]

Interesting, I didn't know about the BriefSky site! When I look at the "Today" section, I can see that from 12-4 AM it shows precipitation, with amounts over 0.36 mm/hr, although still much less than actually fell.

I assume what's going on here is this is the forecast rather than the current conditions? Is the forecast for the current hour generally more accurate than the "current conditions" when it comes to precipitation?

[cloneofghosts]

I assume what's going on here is this is the forecast rather than the current conditions? Is the forecast for the current hour generally more accurate than the "current conditions" when it comes to precipitation?

Brief Sky by default uses Open-Meteo as a source and you need to switch provider (and provide it an API key) to use Pirate Weather. That bar below does show the forecast for the current day (or for PW the next 24h for the current day)

The current conditions primarily come from a different source than the hourly forecast but generally the forecasted conditions are better than the current conditions. There will hopefully be improvements coming to the current conditions to make it better but again no ETA on that.

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