That looks excellent! Thanks for sharing! On Monday, June 29, 2026 at 10:07:38 AM UTC-5 [email protected] wrote:
> I updated my method to include a factor from my VP2 radiation sensor. > > > > On Friday, June 26, 2026 at 5:19:08 PM UTC-4 Vince Skahan wrote: > >> You know sunrise sunset from weewx so it’s possible to tweak the code >> accordingly too… >> On Friday, June 26, 2026 at 1:53:00 PM UTC-7 David Hathaway wrote: >> >>> Very cool to see it in python! I only note that the AI agent added a >>> daylight adjustment: >>> >>> *Step 3: Daylight Adjustment for WBGT* >>> - Daylight is defined locally as approximately 6:30 AM – 8:15 PM in >>> summer for Sugar Land, TX. >>> - Because it is daytime and the sun is contributing radiant heat, the >>> following adjustment is applied: >>> >>> WBGT ≈ Tw + ((T − Tw) × 0.35) + 3.5 >>> >>> This accounts for the additional heat load from direct sunlight. >>> >>> *Result:* WBGT = 92.3 °F >>> >>> That added 7 degrees, which ain't nothing. Not sure if it is valid, but >>> it gets it closer to how I feel outside. 95F at mid day here in the Gulf >>> Coast doesn't feel like a comfy 85F, it feels way hotter. >>> >>> The other suggestion is to add the warning text. The whole reason I >>> started looking at WBGT was because my sports trainer friend said that >>> based on those categories, sports teams are mandated different things. >>> Like maybe a cooler with ice and a tarp, so that if a player falls out >>> because it is Extreme they are wrapped in an ice cocoon. >>> >>> Dave >>> >>> On Friday, June 26, 2026 at 11:44:29 AM UTC-5 [email protected] wrote: >>> >>>> I added this to the new-belchertown skin. >>>> Straightforward. >>>> Add user.wetbulb.WetBulbService to data_services line >>>> Add wetbulb.py to your weewx-data/bin/user directory >>>> Drop index_hook_after_charts.inc into /skins/new-belchertown >>>> Restart weewx and then weectl reports run >>>> >>>> Look at the bottom of the page and you should see the status >>>> >>>> >>>> >>>> >>>> On Tuesday, June 23, 2026 at 3:35:59 PM UTC-4 David Hathaway wrote: >>>> >>>>> Very interesting! I have been asking an AI agent to estimate the WBGT >>>>> for me, and now I asked it what it was using. It uses the Stull formula >>>>> and then a crude radiant heat adjustment. I think it is close enough for >>>>> me to caution my wife to come in frequently so she doesn't perish. I'm >>>>> frequently surprised that the WBGT is lower than our actual temperature >>>>> and >>>>> far below the "feel's like" that we are accustomed to. >>>>> >>>>> The agent says: >>>>> >>>>> *WBGT Calculation – Full Explanation* >>>>> >>>>> The process follows the weather-wbgt-safety skill, which uses local >>>>> WeeWX data and standard approximations suitable for practical heat-stress >>>>> assessment. >>>>> >>>>> *Step 1: Data Source* >>>>> - The local RSS file at /www/rss.xml is read directly. >>>>> - Current values extracted: >>>>> – Outside Temperature (*T*): 95.4 °F >>>>> – Outside Humidity (*RH*): 65 % >>>>> – Wind: calm (not used in the WBGT formula here) >>>>> – Timestamp: 13:40 CDT (used to determine daylight) >>>>> >>>>> *Step 2: Wet-Bulb Temperature (Tw)* >>>>> Wet-bulb temperature is calculated using *Stull’s approximation* (a >>>>> reliable, widely used empirical formula that avoids needing a full >>>>> psychrometric chart). >>>>> >>>>> 1. Convert *T* from °F to °C. >>>>> 2. Apply Stull’s formula (all temperatures in °C, RH in %): >>>>> >>>>> Tw = T × atan(0.151977 × √(RH + 8.313659)) + atan(T + RH) − atan(RH − >>>>> 1.676331) + 0.00391838 × (RH¹·⁵) × atan(0.023101 × RH) − 4.686035 >>>>> >>>>> 3. Convert the resulting *Tw* back to °F. >>>>> >>>>> *Result:* Wet-bulb temperature = 85.3 °F >>>>> >>>>> *Step 3: Daylight Adjustment for WBGT* >>>>> - Daylight is defined locally as approximately 6:30 AM – 8:15 PM in >>>>> summer for Sugar Land, TX. >>>>> - Because it is daytime and the sun is contributing radiant heat, the >>>>> following adjustment is applied: >>>>> >>>>> WBGT ≈ Tw + ((T − Tw) × 0.35) + 3.5 >>>>> >>>>> This accounts for the additional heat load from direct sunlight. >>>>> >>>>> *Result:* WBGT = 92.3 °F >>>>> >>>>> *Step 4: Risk Classification* >>>>> The value is compared against standard thresholds (in °F): >>>>> >>>>> - < 80 → Low >>>>> - 80–85 → Moderate >>>>> - 85–88 → High >>>>> - 88–90 → Very High >>>>> - > 90 → Extreme >>>>> >>>>> At 92.3 °F the conditions fall into the *Extreme* category, >>>>> triggering the safety guidance. >>>>> >>>>> This method gives a practical, conservative estimate without requiring >>>>> specialized instruments (black-globe thermometer, etc.). It is intended >>>>> for >>>>> personal decision-making rather than official occupational safety >>>>> compliance. >>>>> On Tuesday, June 23, 2026 at 2:19:25 PM UTC-5 Rainer Lang wrote: >>>>> >>>>>> the story is rather simple - it refers to how WGBT is determined and >>>>>> what is supported by them. >>>>>> The general formula for determining WBGT outdoors is: >>>>>> WGBT = 0.7 x Tnwb + 0.2 x Tg + 0.1 x Ta >>>>>> where nbw is natural wet bulb, g is BGT and a is outdoor temperature >>>>>> - to get Ta in an Ecowitt context, you need an outdoor T&H sensor >>>>>> (e.g. WH32) >>>>>> - to get Tg in an Ecowitt context, you need a WN38 Black Globe >>>>>> Temperature sensor >>>>>> - to get Tnwb there is no sensor provided - therefore an >>>>>> approximation method is being used >>>>>> only in this combination Ecowitt provides WBGT data >>>>>> and as WBGT has a medical dimension, the disclaimer is on there in >>>>>> their (Ecowitt) web shop >>>>>> >>>>>> there are basically two approximation methods for determining Tnwb and >>>>>> Tg >>>>>> 1. the so-called Stull formula which uses temperature, humidity and >>>>>> air pressure (and derived entities like water saturation pressure) >>>>>> 2. the so-called Lijlegren approximation which also uses wind speed >>>>>> and, depending on the accuracy targeted, also sometimes solar radiation >>>>>> values (direct, indirect, at different wave-lengths ...) >>>>>> >>>>>> 1. the Stull approximation implemented in the firmware now (and used >>>>>> by many others) can lead to a deviation of up to 3° C >>>>>> 2. is quite a sophisticated approach with several iterations, >>>>>> depending on if the approach is used for Tnwb only or for Tnwb + Tg >>>>>> and if solar values are included or not >>>>>> >>>>>> >>>>>> to program the full Lijegren approach to reach a < 0.1% deviation >>>>>> from a nbw-sensor, a coding of 300 - 400 lines of code is needed due to >>>>>> repetetive iterations (so 'they' say) >>>>>> - for so-called "medical" (health related) purposes, a simplified >>>>>> Lijlegren approach can be used also using wind speed and it produces a >>>>>> deviation of < 0.3° C - that's sufficient for the WGBT tiers/windows >>>>>> used >>>>>> in different areas >>>>>> - Ecowitt is considering to replace the Stull formula used now by a >>>>>> simplified Llijlegren approach including wind speed to reach a higher >>>>>> degree of accuracy >>>>>> so, the accuracy of WBGT values provided by any piece of weather >>>>>> station firmware or data logging software (like weewx) will depend on >>>>>> the >>>>>> approach used. >>>>>> >>>>>> >>>>>> On 23.06.2026 20:38, David Hathaway wrote: >>>>>> >>>>>> Thanks for the discussion pointer. I'll go snoop. >>>>>> >>>>>> On Tuesday, June 23, 2026 at 1:09:37 PM UTC-5 Vince Skahan wrote: >>>>>> >>>>>>> I recently saw mention of https://shop.ecowitt.com/products/wn38 >>>>>>> which has a disclaimer that I didn't look into further. >>>>>>> >>>>>>> *"The WN38 Black Globe Thermometer measures and displays the black >>>>>>> globe temperature only, which can be viewed on the LCD screen or >>>>>>> through >>>>>>> the Ecowitt or WS View Plus app.* >>>>>>> >>>>>>> *To display WBGT (Wet Bulb Globe Temperature) data in the app, the >>>>>>> WN38 must be used together with an Ecowitt outdoor temperature and >>>>>>> humidity >>>>>>> sensor from either an outdoor array or a WN32(WN31 is not feasible)."* >>>>>>> >>>>>>> There is a lot of discussion at >>>>>>> https://www.wxforum.net/index.php?topic=49316.0 which might be >>>>>>> worth a read. Hope this helps. >>>>>>> On Wednesday, June 10, 2026 at 10:03:28 AM UTC-7 David Hathaway >>>>>>> wrote: >>>>>>> >>>>>>>> There is a 'wetbulp.py' (note the p) in this group that calculates >>>>>>>> it as a xtype_service. This conversation, >>>>>>>> >>>>>>>> https://groups.google.com/g/weewx-user/c/FntQukhWY00/m/lM53yFt7AwAJ >>>>>>>> >>>>>>>> >>>>>>>> On Wednesday, June 10, 2026 at 11:48:33 AM UTC-5 Vince Skahan wrote: >>>>>>>> >>>>>>>>> Quick search seems to say a WeatherFlow Tempest station has this, >>>>>>>>> but I can't find it mentioned in any of their API so I don't see a >>>>>>>>> way to >>>>>>>>> get it into weewx for this one model station - >>>>>>>>> https://community.tempest.earth/t/wet-bulb-globe-temperature/14386/11 >>>>>>>>> >>>>>>>>> Other threads and docs with the formula seem to say you need >>>>>>>>> special sensors for this, so I can't speculate how WeatherFlow fakes >>>>>>>>> something to generate that item. >>>>>>>>> >>>>>>>>> On Wednesday, June 10, 2026 at 8:36:45 AM UTC-7 David Hathaway >>>>>>>>> wrote: >>>>>>>>> >>>>>>>>>> As the FIFA World Cup (tm) ramps up, we here in Houston are >>>>>>>>>> getting a load of notices about how there is a mandatory water break >>>>>>>>>> in >>>>>>>>>> matches, even though it is played indoors. :-/ As I discussed this >>>>>>>>>> with my >>>>>>>>>> friend the sports trainer, he mentioned that Texas now has a rule >>>>>>>>>> that they >>>>>>>>>> must do certain things according to the WBGT. >>>>>>>>>> >>>>>>>>>> I have searched here for wet bulb additions to WeeWx. I see >>>>>>>>>> discussions from 2024 and wonder if there is someone with a more >>>>>>>>>> recent >>>>>>>>>> idea about implementing this. Does anyone calculate the Risk Level >>>>>>>>>> and >>>>>>>>>> provide Guidance? >>>>>>>>>> >>>>>>>>>> I am trying out an agentic Ai to read the RSS XML feed; It loves >>>>>>>>>> this format. I've not messed with the RSS export. Is there some >>>>>>>>>> intrisic >>>>>>>>>> gotcha? I really only care about current values. >>>>>>>>>> >>>>>>>>>> Dave >>>>>>>>>> >>>>>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "weewx-user" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>> send an email to [email protected]. >>>>>> To view this discussion visit >>>>>> https://groups.google.com/d/msgid/weewx-user/29861e34-51f9-4df4-86e0-c9e06cdbdda0n%40googlegroups.com >>>>>> >>>>>> <https://groups.google.com/d/msgid/weewx-user/29861e34-51f9-4df4-86e0-c9e06cdbdda0n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>> . >>>>>> >>>>>> -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/weewx-user/d4a81929-d1f0-4ec4-926b-20e42d843910n%40googlegroups.com.
