# Excessive rainfall adjustment **URL:** \ **Category:** Tempest Owners\ **Tags:** tempest\ **Created:** [February 18, 2026, 12:58am UTC](https://community.tempest.earth/t/excessive-rainfall-adjustment/28062 "2026-02-18T00:58:23Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![Lux4rd0](https://sea2.discourse-cdn.com/flex020/user_avatar/community.tempest.earth/lux4rd0/32/11359_2.png) [@Lux4rd0](https://community.tempest.earth/u/Lux4rd0)\ **Post date:** [February 19, 2026, 11:25pm UTC](https://community.tempest.earth/t/excessive-rainfall-adjustment/28062/2 "2026-02-19T23:25:54Z")
I can confirm this — we log every `obs_st` WebSocket observation to a database across a collection of Tempest devices, and can see the exact moment each correction happens at the minute level. ### What we’re seeing On February 19th, one of our stations recorded 60 minutes of rain. Summing the per-minute `precipitation_amount_mm` (index 12) values give **12.72 mm (0.50 in)** for the day. But the final `precipitation_amount_local_day_mm` (index 18) was **7.88 mm (0.31 in)** — matching the WeatherFlow app. That’s a 61% overcount from per-minute sums. The daily accumulator was adjusted downward **five separate times** during the day, both during active rain and during dry periods afterward. All timestamps UTC: **During active rain:** | Time (UTC) | `precipitation_amount_mm` | `precipitation_amount_local_day_mm` | | --- | --- | --- | | 17:05:00 | 0.503085 | 3.489566 | | **17:06:00** | **0.493703** | **2.896266 (−0.59 mm)** | | 17:07:00 | 0.577019 | 3.473285 | At 17:06, the station reported 0.49 mm of rain that minute — `local_day` should have gone UP to ~3.98. Instead, it dropped to 2.90. | Time (UTC) | `precipitation_amount_mm` | `precipitation_amount_local_day_mm` | | --- | --- | --- | | 17:20:00 | 0.593057 | 6.876617 | | **17:21:00** | **0.668407** | **5.065174 (−1.81 mm)** | | 17:22:00 | 0.785958 | 5.851132 | **During dry periods:** | Time (UTC) | `precipitation_amount_mm` | `precipitation_amount_local_day_mm` | | --- | --- | --- | | 19:00:00 | 0 | 10.599377 | | **19:01:00** | **0** | **7.113013 (−3.49 mm)** | | 19:02:00 | 0 | 7.113013 | The largest adjustment — 3.49 mm removed from the daily total while no rain was falling. Two smaller corrections followed at 21:21 UTC (−0.07 mm) and 22:24 UTC (−0.10 mm). ### It’s not station-specific We checked all 15 Tempest devices in our collection that have recorded rain over the past 90 days: | Metric | Value | | --- | --- | | Devices with rain data | 15 | | Devices showing mid-day `local_day_mm` drops | **15 (100%)** | | Total downward adjustments (90 days) | **757** | | Largest single drop | −41.21 mm | | Average drop | −2.10 mm | Every device that has recorded rain shows this pattern. The corrections happen on every rainy day, multiple times per event. ### The nearcast/analysis fields are redundant now On all 757 drops across all 15 devices, `precipitation_analysis_type` (index 21) is **always 0,** and the nearcast fields (indices 19, 20) are **identical copies** of the base fields (indices 12, 18). This lines up with what was discussed in the [Changes to precipitation API](https://community.tempest.earth/t/changes-to-precipitation-api/27650) thread — all four precipitation fields now return the same RainCheck-corrected data. The analysis type flag and nearcast fields appear to be vestigial. ### For anyone building integrations The per-minute `precipitation_amount_mm` is corrected at the time of emission but **never retroactively adjusted** when RainCheck later revises its estimate downward. The running daily total `precipitation_amount_local_day_mm` **is** adjusted in real-time. So: - **Don’t sum `precipitation_amount_mm` for daily totals** — it will overcount. - **Use `precipitation_amount_local_day_mm`** — It’s the authoritative value and matches the WeatherFlow app. - **Raw, uncorrected data** is only available via UDP from the local hub. * * * --- _[View the full topic](https://community.tempest.earth/t/excessive-rainfall-adjustment/28062)._