About the Data
Types of data sources
Observational / weather-station data: Pakistan Meteorological Department (PMD) and NOAA observations come from physical observing stations and ground-based sensors. Where PakClimate archives these observations, the originating provider, station identity and parameter provenance are retained.
PakClimate can process high-spatial-resolution ERA5-Land hourly source data for coordinate-level climate analysis across Pakistan. Hourly temperature, dew point, wind components, surface pressure and precipitation are converted into documented local-day climate statistics while preserving source provenance. Published city archives remain source-specific and are not silently blended.
Reanalysis / gridded model-derived data: NASA POWER / MERRA-2 and ERA5-Land (Copernicus) are gridded historical datasets rather than measurements from a weather station at the selected city. They are kept separate from station observations and are identified explicitly when selected.
PakClimate Forward Archive: PakClimate is the compiler/archive, not a weather station. The archive retains the actual upstream observational/provider provenance for each parameter where available, including PMD where applicable.
Understanding the historical data sources
These datasets are distinct. A gridded climate estimate is not a reading from a physical weather station. Availability differs by city, parameter and latest imported date.
NASA POWER means Prediction Of Worldwide Energy Resources, NASA's data access service. PakClimate uses its meteorological daily series, primarily derived from MERRA-2 (Modern-Era Retrospective analysis for Research and Applications, Version 2), a global atmospheric reanalysis. The POWER meteorological daily record generally begins in 1981. Recent POWER data may use an additional near-real-time processing system; see the source-specific metadata.
ERA5-Land (Copernicus) is a land-surface climate reanalysis from the European Centre for Medium-Range Weather Forecasts through the Copernicus Climate Data Store. It provides hourly gridded estimates beginning in 1950. PakClimate derives daily summaries from its imported hourly records. Dataset DOI: 10.24381/ee82e357.
NOAA means the US National Oceanic and Atmospheric Administration; PakClimate uses available station-based historical observations. Their dates depend on the station and variable. PMD means the Pakistan Meteorological Department, an observational source used where available for current conditions and forward collection.
PakClimate Forward Archive is PakClimate's independently selectable, continuously accumulating daily archive, collected from the city's individual activation date in September or October 2026 onward. It records provider provenance, including PMD and Open-Meteo where applicable. It is not a continuation of NASA or Copernicus data under the same source label.
Where an external historical series ends before December, select PakClimate Forward Archive to inspect the subsequent period. Values from different sources are not silently joined or averaged in the individual-source charts.
Archive coverage at a glance
These dates describe records already imported into PakClimate, not the full availability of the upstream products. Coverage differs by city and parameter.
Exact NASA and NOAA date bars are withheld until D1 coverage endpoints have been verified. No approximate coverage graphic is presented as a measured record.
Source separation
PMD and NOAA observational records, NASA POWER / MERRA-2, ERA5-Land (Copernicus), and the PakClimate Forward Archive are retained as distinct source layers. Where a page offers a source selector, calculations, charts and records are recomputed from the selected source only. PakClimate does not silently average one source with another or use one dataset to conceal gaps in another.
Coverage & missing data
A station's period of record is not assumed to mean continuous daily coverage. PakClimate counts actual available dates and parameter values. Missing dates remain explicit. Current/recent observations are not promoted into the historical archive until their source and daily-summary semantics are verified.
Source precedence
Historical Records and general long-term parameters: NASA POWER / MERRA-2 is the default historical layer. Observed maximum/minimum parameters and extremes: NOAA station observations are preferred where available. Search by Date from 10 September 2026 onward: the PakClimate Historical Archive is the default. Sources are not averaged or silently substituted for one another.
ERA5-Land · temperature and precipitation
Hourly 2 m air temperature is converted from kelvin to Celsius before local-day extrema are calculated.
ERA5-Land total precipitation is converted from metres of water equivalent to millimetres. PakClimate reports a daily precipitation total, obtained by summing the valid non-overlapping hourly precipitation increments assigned to the local day.
ERA5-Land · wind speed from vector components
ERA5-Land provides eastward and northward 10 m wind components, u and v, in m/s. PakClimate first calculates each hourly scalar wind speed, converts it to km/h, and then calculates the daily statistics.
The mean of hourly scalar magnitudes is kept distinct from resultant vector speed because they describe different properties of a changing wind field.
ERA5-Land · atmospheric pressure
Surface pressure is converted from pascals to hectopascals and the published daily field is the arithmetic mean of valid hourly surface-pressure values.
Surface pressure is elevation-dependent and should not be confused with sea-level pressure.
Browser compatibility
PakClimate climate charts are delivered from the site's chart service. Some browser content blockers can prevent these charts from loading; if a chart is unexpectedly unavailable, allow pakclimate.com in the content blocker and reload the page. Homepage photography is supplied with modern WebP plus a conventional JPEG fallback for broader browser compatibility.
Methodology principle
Raw source → validation → source-specific PakClimate archive → calculations → website. No fabricated values, no silent source merging, and no unlabelled station changes.
Parameters, daily statistics and units
PakClimate distinguishes the physical unit from the daily statistic being published. The table below states the convention used on charts, summaries and daily records.
| Parameter | PakClimate unit | Published daily statistic | ERA5-Land basis |
|---|---|---|---|
| Maximum temperature | °C | Daily maximum | 2 m air temperature in K |
| Minimum temperature | °C | Daily minimum | 2 m air temperature in K |
| Precipitation | mm | Daily precipitation total | Total precipitation in m of water equivalent |
| Relative humidity | % RH | Daily mean relative humidity | Derived from 2 m temperature and 2 m dew-point temperature |
| Wind speed | km/h | Daily mean; daily maximum where available | 10 m eastward and northward components in m/s |
| Wind direction | degrees (0–360°) | Daily resultant direction where representative | Derived from 10 m vector components; meteorological “from” convention |
| Surface pressure | hPa | Daily mean surface pressure | Surface pressure in Pa |
Wind-direction convention: 0°/360° = north, 90° = east, 180° = south and 270° = west. The bearing states the direction from which the wind comes.
General units & conversions
PakClimate publishes normalized units consistently while retaining source provenance. Source-native values are converted only by documented conversions; missing or sentinel values remain null rather than being converted to zero.
Daily rollover & observed extrema
PakClimate's forward archive uses observations captured during the day. Running maximum and minimum temperatures are updated from incoming observations, then finalized only after the local calendar day ends. Forecast daily maxima/minima are not promoted as observed PakClimate records. If a source does not provide a verified daily parameter, that field remains null rather than being inferred silently.
ERA5-Land (Copernicus) · gridded reanalysis
PakClimate stores ERA5-Land as a separate source labelled ERA5-Land (Copernicus). The source product is the Copernicus Climate Change Service (C3S) ERA5-Land hourly time-series data from 1950 to present, DOI 10.24381/ee82e357. It is a gridded reanalysis product, not a physical weather station, so station/WMO/ICAO fields are intentionally left blank. PakClimate currently derives daily records for selected cities from the original hourly Copernicus files and stores only the derived daily rows in D1; the original hourly downloads are retained separately for reproducibility and deeper analysis.
ERA5-Land · local-day aggregation
Hourly timestamps are assigned to the appropriate local civil day for the city before daily statistics are calculated. This prevents a UTC midnight boundary from splitting Pakistan's daytime cycle across two published dates. A daily record is emitted only from the hourly observations belonging to that local date; incomplete boundary days are not silently padded with hours from another date. This is why the usable daily archive can begin later than the first timestamp contained in a downloaded hourly file.
ERA5-Land · relative humidity from dew point
Where relative humidity is not supplied directly, PakClimate derives hourly RH from 2 m air temperature T and 2 m dew-point temperature Td, with both temperatures expressed in °C.
Hourly RH is constrained to 0–100%. The published daily humidity value is the arithmetic mean of valid hourly RH values, not a daily maximum.
ERA5-Land · daily wind direction and variability
PakClimate averages the hourly vector components first, then calculates the resultant vector and meteorological bearing.
Direction is the meteorological direction from which the wind came. The coherence/resultant ratio C compares resultant magnitude with mean scalar speed. When the adopted variability criterion indicates that a single daily bearing would be misleading, the speed record is retained but direction is reported as Variable rather than forcing a compass sector.
ERA5-Land · provenance and source precedence
Every ERA5-Land row retains source era5land, provider Copernicus Climate Change Service (C3S), product identity and DOI 10.24381/ee82e357. ERA5-Land is exposed as an explicitly selectable historical source where available; it is not silently blended with NOAA, NASA POWER or the PakClimate Forward Archive. Existing source precedence remains intact for canonical/preferred records: observational station data are preferred where the relevant page calls for observations, NASA POWER/MERRA-2 remains the established gridded historical baseline, and PakClimate Forward Archive remains the forward operational archive. Selecting ERA5-Land means calculations are performed from ERA5-Land records only.
Update cadence
Current conditions and the PakClimate forward archive continue on their operational daily cycle. Historical aggregate pages that do not require daily source refresh are reviewed on a monthly source-update cadence. Daily rollover does not override source precedence or page-specific update behaviour.
Air Quality and UV Index
Current US Air Quality Index (US AQI), PM2.5, PM10 and UV Index are supplied by Open-Meteo's Air Quality API, using model-derived atmospheric products including Copernicus CAMS. These are estimates for model grid cells, not direct readings from local PMD or air-monitoring stations. The API returns timestamps and concentrations in µg/m³ for particulate matter.
The overall US AQI is the highest applicable pollutant-specific sub-index; individual pollutants may use different averaging periods. The Current Conditions card identifies the leading pollutant using the largest available returned sub-index. PM2.5 and PM10 values on the card are current modelled concentrations, not rolling 24-hour means or claims of safety. The site does not currently archive these environmental values or compare them against WHO daily guidelines.
UV Index is a separate exposure indicator. Standard categories are Low (below 3), Moderate (3 to below 6), High (6 to below 8), Very High (8 to below 11) and Extreme (11 or higher). The violet gradient is a visual intensity cue; the category label supplies the risk classification. Values may be unavailable or delayed; environmental readings are independent of PMD-first weather observations and the PakClimate Forward Archive.
Source: Open-Meteo Air Quality API documentation. Provider licensing and attribution requirements should be verified before production release.