Rain Intensity values

In case you were wondering about rain intensity descriptive values on the DASHBOARD CARD VIEW of the app. These are specifically designed to give the average home user a simple and quick understanding of rain intensity. Actual values are published both on the rain graph and on the LIST VIEW in the apps.

VERY LIGHT: < 0.25 mm/hour
LIGHT: ≥ 0.25, < 1.0 mm/hour
MODERATE: ≥ 1.0, < 4.0 mm/hour
HEAVY: ≥ 4.0, < 16.0 mm/hour
VERY HEAVY: ≥ 16.0, < 50 mm/hour
EXTREME: > 50.0 mm/hour


I’m curious about determination of the rain intensity, Can I know if this value (that determine the light rain or heavy rain) came from WeatherFlow or NOAA?

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After much research, we found no real global standard for rain intensity. That said, we based the rain intensity for SKY on the following sources. The sensitivity of SKY exceeds the ability of a common rain bucket collector to determine instantaneous rain intensity…so it’s relatively new territory…and the terms are intended to be soft descriptors for the average home owner to quickly reference.


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thanks to illustrate the rainfall intensity, but I’ve noticed some SKY station that have rain but I’m get confused by the rain graph. ea8a5599-d19f-4cff-836e-26a0b2929b8c

as you can see in the picture the green line(Accumulation) is less than the blue tower(rain rate) even when the rain rate record 46mm, the accumulation stay at 19mm!??
Can you please explain the Rain graph to clear the confusion?.

The scale shown on the left side is only for accumulated rain. The bars show the rainfall rate but on an entirely different scale (which probably should be shown on the right side of the graph in a color to match the bars, but that is probably a feature request for WF staff). If you tap or click on one of the bars you should see at the top of the screen the accumulated rain and the instantaneous rate for that bar.


You left out;

Holy $@#? Extream > 200mm/hour

Also known as “Build an Ark”


@todayweather4 What is the station ID for the graphs you referenced? Try zooming into the 1min temporal resolution for better granularity. The 1min observations report total accumulation in one minute. The 1min graph shows the rate (total/min) converted to /hour. The other temporal resolutions sum up the totals for that time period and show the rate for the given time period. For example, the 5-min bucket is the sum of five 1-min obs, divided by 5 minutes, converted to /hour. And the 30-min bucket is the sum of thirty 1-min obs, divided by 30 minutes, converted to /hour…and so on.


this is the station that I’m reference to Weather station
and your explanation illustrate many things for me but I’m sorry because it’s not clear my confusion, the things that makes me confused is on this picture below
the rain tare is 125mm/h but the accumulation is 70mm less than the rain rate

and when I zoom out to the last graph I see the accumulation is 63mm
but when I zoom in I found the accumulation is 74mm

sorry to put many photos on my post but I want to illustrate my confusion more better.

Yes that is the way it should be. 125mm would only show up as the accumulation if that 125mm/hr rate lasted for a full hour. Since 125mm/hr only lasted for 1 minute (and other rain rates were lower) you total accumulation will be less.


Think of rain rate as driving speed. You can drive 100 km/h for 6 minutes (0.1 hour) and only have traveled 10 km. Similar to what @hankster said, you would have to drive 100 km/h for a whole hour to have traveled the full 100 km.


Or think of it as a water pump. You can pump at 360 gallons an hour. But in one minute you only get 6 gallons.


thanks so much to you guys @hankster @gizmoev and @GaryFunk for your explanation and to provide a different examples, you guys clear my confusion and I’m fully knowledge of it, I don’t know why i don’t think of it as a speed (per hour).

Great question, and while it sounds like this is mostly cleared up, I thought I’d officially summarize how the rain graph is supposed to work:

The blue bar represents the average hourly rate for the time period shown, while the green line represents the daily accumulation (since midnight in the local timezone). The left axis scale applies to both values, but you need to add “per hour” to the rate data. The time period that applies to the blue bar (rate) changes based on zoom level: 1 minute, 5 minute, 30 minute, 3 hour, 1 day. In general the further you zoom in the higher the individual rate values will be, since there is more averaging as you zoom out. Note that when you zoom all the way out, to the 1 day per time step graph, the blue bar (average rate) is not shown.


Thanks for the clarification of the graphics!

The chosen six categories (i.e. very light rain, light rain, etc.) seem to have been developed in temperate areas, which differ significantly in rainfall characteristics when compared to the (humid) tropics, with their higher rain rates. Other thresholds are proper for such conditions.

For more universal use it would be useful to revert back to showing actual calculated rain rates in mm/h as shown in the graphics above. Presently, both apps (Android and iOS), as well as the web, do not show such values. Moreover, several of my blue bars are cut off at temporal scales of interest (e.g. when flash flooding may occur). Would it be possible to scale the graphic according to maximum rates in the data?

I only have the WF up and running for one day so I’m still a newbie getting into stuff.


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See update on display of rain rates here: Rain rate mismatch between Windows and Android

@pachuquear Welcome to the fun. The instantaneous rain rate stated in units/time can be seen in the ‘list view’ data in the apps — click the icon in upper right corner. Historical rain rates as a function of volume/time for dynamic time scales are not published on the graphs for a myriad of reasons. (Remember, the core design audience in the average home owner.) The vertical scale on the rain graphs will dynamically adjust to accommodate your rain accumulation values, even in the tropics.

The blue bars denote rain intensity in seven categorical buckets as described here: https://weatherflow.github.io/SmartWeather/api/derived-metric-formulas.html These categories were informed by a complete analysis of global rain accumulation standards. The blue bars are not related to the vertical scale for accumulation, but rather are to be used to view the rain intensity during the time period per the noted intensity categories. 1-min rain accumulation data can be collected locally via UDP for those who desire the raw data.


Thanks for your response.

I’m aware of the how the categories have been defined and the list view. I still find that it would be far more useful with the actual rates than categories. With respect to these categories please share the reference to the study mentioned (i.e. a complete analysis).

I will look into how to get the 1-min data…

On another note, yesterday suggested a rainfall rate of 656.9 mm/h. This is – of course – a drastic exaggeration.


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Hi @pachuquear

We agree on the utility (we’re data wonks after all!), but in practicality, it presented a range of problems, questions, and issues. For those users who require this level of granular data, the HUB will publish via UDP. See other threads about collection of raw data via UDP.

Oh gosh, this was done over a year ago by our team of meteorologists. Don’t have our notes in hand, but we can tell you that multiple trained mets surveyed a range of global standards to arrive at the consensus categories.

Don’t panic. As noted extensively in other threads – we have not released the WF auto-calibration / applied machine learning system for rain accumulation yet. It’s coming soon and when released, you will see a drastic improvement in the rain accum values.


I think here we see the first step within the firmware update to v94


Here’s a more recent update: Rain dashboard vs. reality