St Nicholas Weather was founded in November 2021 by Benjamin Raisanen, following his purchase of a small weather station. Soon after, data publication began, using commercial software developed by Weather Underground and WeatherCloud.
In January 2025, the station was replaced with an Ecowitt WS90, with the aim of improving data quality. This also enabled integration with the Met Office’s hyperlocal weather observation project, which has since been deprecated.
St Nicholas Weather now stores data with WOW-BE, an open source project by the Belgian weather service, which is unlikely to face future closure for commercial reasons.
Benjamin also writes a blog on the St Nicholas Weather website, looking at events to do with our weather and climate. He writes infrequently, but aims to cover interesting topics when he does write.
Our approach
1. Accessible data
St Nicholas Weather aims to ensure that our data is accessible to everyone. Our data is open source and can be accessed through WOW-BE, meaning it is available to people, the public sector, non-profits, and research institutions.
2. Transparency
St Nicholas Weather aims to be transparent about how our data is valuable, which is set out in the WMO-No. 8 assessment. Due to legal and technical constraints, our data cannot match the quality of an official station.
WMO-No. 8 assessment
The Ecowitt WittBoy Pro is operated as a semi-rural automatic weather station at approximately 104 m above sea level in St Nicholas, Vale of Glamorgan, Wales. Its installation and observing practices have been assessed against the relevant principles of the WMO Guide to Instruments and Methods of Observation (WMO-No. 8).
The station has good general exposure for a personal weather station, with a grass surface, stable mounting and relatively open surroundings. However, nearby buildings and trees affect wind exposure from some directions, while the WS90’s integrated precipitation sensor and lack of traceable calibration limit direct equivalence with professional WMO observing systems.
The assessment therefore represents alignment with WMO observing practices rather than formal WMO compliance or certification. Chapters concerning observations that the station does not perform are marked as not applicable.
Site data
Station: Ecowitt WittBoy Pro (HP2564 / WS90)
Location: St Nicholas, Vale of Glamorgan, Wales
Site: Semi-rural garden, approximately 104 m above sea level
Assessment basis: WMO-No. 8, 2021/2018 edition; assessment of the installed observing system rather than manufacturer specifications alone.
Compliance
| WMO-No. 8 section | Applicability | Compliance | Assessment |
|---|---|---|---|
| Volume I, Ch. 1 — General | Applicable | 🟠 Partial | The station has a defined location, known elevation, stable mounting and continuous automated observations. Its semi-rural setting is favourable. Formal WMO-style metadata, QC and calibration procedures have not yet been established. |
| Volume I, Ch. 2 — Measurement of temperature | Applicable | 🟠 Partial | Grass surface and semi-rural surroundings provide good environmental conditions. The sensor is approximately 2.4 m above ground and exposed to sunlight. A radiation shield is present, but the WS90 arrangement is not equivalent to a conventional WMO reference screen. |
| Volume I, Ch. 3 — Measurement of atmospheric pressure | Applicable | 🟢 Good | Station elevation is known at approximately 104 m ASL. Pressure observations are slightly lower than the nearby official station in a manner consistent with the elevation difference. Formal traceable calibration has not been performed. |
| Volume I, Ch. 4 — Measurement of humidity | Applicable | 🟠 Partial | Semi-rural exposure and separation from buildings are favourable. The integrated WS90 humidity sensor provides useful observations, but there is no documented traceable calibration against a reference hygrometer. |
| Volume I, Ch. 5 — Measurement of surface wind | Applicable | 🟠 Partial | The mast is stable and the wind sensor is aligned to north. However, the approximately 2.4 m sensor height is well below the standard reference height used for many surface-wind observations. Houses and trees also produce direction-dependent airflow disturbances. |
| Volume I, Ch. 6 — Measurement of precipitation | Applicable | 🟠 Partial | The semi-rural location and grass surroundings are favourable, but nearby buildings and trees can affect precipitation catch. The WS90’s piezoelectric precipitation measurement has not been independently intercompared against a conventional reference gauge. |
| Volume I, Ch. 7 — Measurement of radiation | Partially applicable | 🟠 Partial | The WS90 provides light and UV measurements and has generally good sky exposure. However, the sensors are not a substitute for calibrated WMO/reference radiation instrumentation. |
| Volume I, Ch. 8 — Measurement of sunshine duration | Applicable in principle | 🔴 Not compliant | The WS90’s light sensor should not be treated as a WMO-standard sunshine-duration instrument without appropriate methodology and instrumentation. |
| Volume I, Ch. 9 — Measurement of visibility | N/A | ⚪ N/A | No dedicated visibility sensor is installed. |
| Volume I, Ch. 10 — Measurement of evaporation | N/A | ⚪ N/A | No evaporation measurement is performed. |
| Volume I, Ch. 11 — Measurement of soil moisture | N/A | ⚪ N/A | No soil-moisture sensor is installed. |
| Volume I, Ch. 12 — Upper-air pressure, temperature and humidity | N/A | ⚪ N/A | The station performs surface observations only. |
| Volume I, Ch. 13 — Measurement of upper wind | N/A | ⚪ N/A | No upper-air wind observations are performed. |
| Volume I, Ch. 14 — Present/past weather; state of ground | Partially applicable | 🟠 Partial | The station records parameters from which some weather conditions can be identified, but it does not perform a complete formal present/past-weather observation programme. |
| Volume I, Ch. 15 — Clouds | N/A | ⚪ N/A | No dedicated cloud-observation or ceilometer system is installed. |
| Volume I, Ch. 16 — Atmospheric composition | Partially applicable | 🟠 Limited | The WH41 provides PM2.5 observations. This is useful atmospheric-composition information but represents only a limited subset of the measurements covered by this chapter. |
| Volume II, Ch. 1 — General cryospheric observations | Limited | 🟠 Partial | Snow occurs at the site but relatively infrequently, with accumulation normally below approximately 3 days of persistent accumulation. No dedicated cryospheric observing system is installed. |
| Volume II, Ch. 2 — Measurement of snow | Limited | 🟠 Limited | Snowfall occurs fewer than approximately 10 days per year, but there is no dedicated WMO-standard snow-depth or snow-water-equivalent measurement system. |
| Volume II, Ch. 3 — Measurement of glaciers | N/A | ⚪ N/A | No glacier observations are applicable to the site. |
| Volume III, Ch. 1 — Measurements at automatic weather stations | Highly applicable | 🟠 Partial | The WittBoy Pro functions as an automated weather station, with continuous measurements and automated transmission to Ecowitt, WOW-BE, Wunderground and WeatherCloud. Long-term data are retained by WOW-BE. Formal WMO-style QC, calibration, metadata and maintenance procedures remain areas for improvement. |
| Volume III, Ch. 2 — Aeronautical meteorological stations | N/A | ⚪ N/A | The station is not an aeronautical meteorological station. |
| Volume III, Ch. 3 — Aircraft-based observations | N/A | ⚪ N/A | No aircraft observations are performed. |
| Volume III, Ch. 4 — Marine observation | N/A | ⚪ N/A | The station is land-based. |
| Volume III, Ch. 5 — Profiling techniques | N/A | ⚪ N/A | No atmospheric profiling system is installed. |
| Volume III, Ch. 6 — Electromagnetic lightning detection | N/A | ⚪ N/A | No dedicated lightning detector is installed. |
| Volume III, Ch. 7 — Radar measurements | N/A | ⚪ N/A | No weather radar system is operated. |
| Volume III, Ch. 8 — Balloon techniques | N/A | ⚪ N/A | No balloon observations are performed. |
| Volume III, Ch. 9 — Urban observations | N/A | ⚪ N/A | The station is located in a semi-rural area of St Nicholas, Vale of Glamorgan, rather than an urban environment. |
| Volume III, Ch. 10 — Road meteorological measurement | N/A | ⚪ N/A | The station is not a road-weather monitoring station. |
| Volume IV, Ch. 1 — Introduction | N/A | ⚪ N/A | This volume concerns space-based observations. |
| Volume IV, Ch. 2 — Earth observation from space | N/A | ⚪ N/A | Not applicable to a ground-based PWS. |
| Volume IV, Ch. 3 — Remote-sensing instruments | N/A | ⚪ N/A | No relevant space-based remote-sensing instrument is operated. |
| Volume IV, Ch. 4 — Satellite programmes | N/A | ⚪ N/A | Not applicable. |
| Volume IV, Ch. 5 — Space-based observation of geophysical variables | N/A | ⚪ N/A | Not applicable. |
| Volume IV, Ch. 6 — Calibration and validation | N/A | ⚪ N/A | Space-based calibration/validation is outside the scope of this station. |
| Volume IV, Ch. 7 — Cross-cutting issues | N/A | ⚪ N/A | Not applicable to the station’s observing system. |
| Volume V, Ch. 1 — Quality Management | Applicable | 🟠 Partial | Multiple data services and long-term data retention are positive. A formal documented quality-management system has not yet been established. |
| Volume V, Ch. 2 — Sampling meteorological variables | Applicable | 🟠 Partial | The WS90 reports observations at approximately 8.8-second intervals. The adequacy of the final sampling/aggregation used by the data services needs to be assessed separately. |
| Volume V, Ch. 3 — Data reduction | Applicable | 🟠 Partial | Data are processed through the Ecowitt ecosystem before being distributed to several services. The complete processing chain and retention of unprocessed observations require further documentation. |
| Volume V, Ch. 4 — Testing, calibration and intercomparison | Highly applicable | 🔴 Limited | No formal traceable calibration or structured reference-instrument intercomparison has been performed. Comparisons with nearby PWSs provide useful evidence but are not equivalent to formal calibration. |
| Volume V, Ch. 5 — Training of instrument specialists | Applicable in principle | 🟠 Partial | The station can be visually inspected and maintained, but there is no formal instrument-specialist training programme. |
Overall assessment
| Assessment category | Result |
|---|---|
| Site classification | 🟢 Semi-rural |
| Site elevation | ~104 m ASL |
| Overall WMO-No. 8 alignment | 🟠 Partial |
| General site suitability | 🟢 Good for a semi-rural PWS |
| Temperature | 🟠 Good/Partial |
| Humidity | 🟠 Good/Partial |
| Atmospheric pressure | 🟢 Good |
| Wind | 🟠 Partial |
| Precipitation | 🟠 Partial |
| Light/UV | 🟠 Partial |
| Snow | 🟠 Limited |
| PM2.5 | 🟠 Limited atmospheric-composition observation |
| Data availability | 🟢 Strong |
| Long-term data retention | 🟢 Strong |
| Automated operation | 🟢 Strong |
| Calibration/intercomparison | 🔴 Limited |
| Formal QC system | 🟠 Partial / developing |
| Formal WMO certification | 🔴 None claimed |
3. Improving our station
St Nicholas Weather aims to improve the station where it is financially feasible to provide a more detailed understanding of the weather and climate, as well as ensuring that we provide the most accurate data possible.