Climate Normals: Terms and Units

Steffi LaZerte


This table shows details regarding original column (measurement) names and units of all climate normals measurements. It further provides links back to the ECCC glossary for more details.

See the ECCC website on climate normals for more details:

For details on weather measurements, see the glossary vignette.

General descriptions

ECCC_name weathercan_name description
Temperature temp Temperature measurements are made from self-registering maximum and minimum thermometers set in a louvered, wooden shelter. The shelter is mounted on a stand so that the thermometers are approximately 1.5 m above ground, which is usually a level, grassy surface.
Rainfall, Snowfall, And Precipitation precip Rain, drizzle, freezing rain, freezing drizzle and hail are usually measured using the standard Canadian rain gauge, a cylindrical container 40 cm high and 11.3 cm in diameter. The precipitation is funneled into a plastic graduate which serves as the measuring device.
Snow Depth snow_depth Snow cover is the depth of accumulated snow on the ground, measured at several points which appear representative of the immediate area, and then averaged.
Number Of Days With Specified Parameters days These elements give the average number of days per month or year on which a specific meteorological event or parameter threshold occurs. In the case of rainfall and precipitation, 0.2 mm or more must occur before a “day with” is counted. The corresponding figure for snowfall is 0.2 cm.
Degree-Days dd Degree-days for a given day represent the number of Celsius degrees that the mean temperature is above or below a given base. For example, heating degree-days are the number of degrees below 18° C. If the temperature is equal to or greater than 18, then the number of heating degrees will be zero. Normals represent the average accumulation for a given month or year.
Soil Temperature soil_temp Soil temperature measurements provide the climatology of soil thermal characteristics such as the depth of frost penetration into the soil and the duration that the soil remains frozen. It is of interest to hydrologists because it affects surface runoff, infiltration and snowmelt and to agriculturalists because it affects seed germination.
Evaporation evaporation Evaporation refers to the calculated lake evaporation occurring from a small natural open water-body having negligible heat storage and very little heat transfer at its bottom and sides. It represents the water loss from ponds and small reservoirs but not from lakes that have large heat storage capacities. Lake evaporation is calculated using the observed daily values of pan evaporative water loss, the mean temperatures of the water in the pan and of the nearby air, and the total wind run over the pan.
Frost And Freezing-Free Period frost Freezing occurs whenever temperatures fall to 0 deg C or lower. Frost data normals are based on the occurrence of freezing temperatures as recorded from minimum thermometers. The “Freezing-free Period” is defined as the number of days between the last occurrence of frost in spring and first occurrence of frost in the fall for a given year. For the purposes of these calculations, “spring” is defined as days on or before July 15, “fall” is defined as days after July 15 and freezing or frost occurs on any day where the daily minimum temperature (Tmin) is observed to be less than or equal to 0 deg C.
Hourly Data hours Some climate elements are observed on an hourly rather than a daily basis. For these elements, the “3 and 5” rule for completeness is inapplicable given the comprehensive volume of data. Instead, to qualify for inclusion, hourly elements must have at least 90% of all available hours for a month complete where means or “days with” statistics are calculated. As with daily elements, where average totals are calculated, the record required 100% complete data. The monthly mean was then assigned an annual code following the completeness requirements.
Wind wind Most principal climatological stations are equipped with a standard type U2A anemometer, taking one-minute or (since 1985) two-minute mean speeds values at each observation. At other wind-measuring sites, values are usually obtained from autographic records of U2A or 45B anemometers. Averaging periods at these sites may vary from one minute to an hour.
Bright Sunshine sun Bright sunshine observations are made using the Campbell-Stokes sunshine recorder. It consists of a glass sphere that is 10 cm in diameter, mounted concentrically in a portion of a spherical bowl. The sun’s rays are focused by the glass sphere on a card held in position by a pair of grooves in the bowl. The focused rays scorch the card or burn a trace right through it. The card size used depends on the length of the day and is available in three classes corresponding to the time of the year equinox, summer or winter solstice.
Humidex humidex Humidex is an index to indicate how hot or humid the weather feels to the average person. It is derived by combining temperature and humidity values into one number to reflect the perceived temperature. For example, a humidex of 40 means that the sensation of heat when the temperature is 30 degrees and the air is humid feels more or less the same as when the temperature is 40 degrees and the air is dry.
Wind Chill wind_chill Wind chill is an index to indicate how cold the weather feels to the average person. It is derived by combining temperature and wind velocity values into one number to reflect the perceived temperature. For example, if the outside temperature is -10°C and the wind chill is -20, it means that your face will feel more or less as cold as it would on a calm day when the temperature is -20°C.
Humidity humidity Vapour pressure is the pressure exerted by the water present in an air parcel. This pressure is one of the partial pressures that make up the total pressure exerted by an air parcel. The vapour pressure increases as the amount of water vapour increases.
Pressure pressure Pressure is the weight of a column of air of unit cross-sectional area extending from the level of the observing station vertically to the outer limit of the atmosphere. The standard instrument for the measurement of atmospheric pressure is the mercury barometer, in which the air pressure is balanced against the weight of a column of mercury in a glass tube that contains a vacuum.
Solar Radiation rad Solar radiation is the measurement of radiant energy from the sun, on a horizontal surface. There are several standardized components of independent measurements. Each component is assigned a different identifying number referred to as Radiation Fields (RF). The standard metric unit of radiation measurement is the Mega Joule per square metre (MJ/m2).
Visibility (Km) visibility Visibility in kilometers (km) is the distance at which objects of suitable size can be seen and identified. Precipitation, fog, haze or other obstructions such as blowing snow or dust can reduce atmospheric visibility.
Cloud Amount cloud A cloud in the atmosphere is a visible collection of minute particle matter, such as water droplets and/or ice crystals, in the air. Condensation nuclei, such as smoke or dust particles, form a surface around which water vapour can condense and create clouds.

Original names and units

These represent the original ECCC measurement names with units and their corresponding measurements in weathercan.


ECCC_name weathercan_name
Daily Average (°C) temp_daily_average
Standard Deviation temp_sd
Daily Maximum (°C) temp_daily_max
Daily Minimum (°C) temp_daily_min
Extreme Maximum (°C) temp_extreme_max
Date (YYYY/DD) temp_extreme_max_date
Extreme Minimum (°C) temp_extreme_min
Date (YYYY/DD) temp_extreme_min_date


ECCC_name weathercan_name
Rainfall (mm) rain
Snowfall (cm) snow
Precipitation (mm) precip
Average Snow Depth (cm) snow_mean_depth
Median Snow Depth (cm) snow_median_depth
Snow Depth At Month-End (cm) snow_depth_month_end
Extreme Daily Rainfall (mm) rain_extreme_daily
Date (YYYY/DD) rain_extreme_daily_date
Extreme Daily Snowfall (cm) snow_extreme_daily
Date (YYYY/DD) snow_extreme_daily_date
Extreme Daily Precipitation (mm) precip_extreme_daily
Date (YYYY/DD) precip_extreme_daily_date
Extreme Snow Depth (cm) snow_extreme_depth
Date (YYYY/DD) snow_extreme_depth_date

Days With Maximum Temperature

ECCC_name weathercan_name
<= 0 °C temp_max_days_<=0
> 0 °C temp_max_days_>0
> 10 °C temp_max_days_>10
> 20 °C temp_max_days_>20
> 30 °C temp_max_days_>30
> 35 °C temp_max_days_>35

Days With Minimum Temperature

ECCC_name weathercan_name
> 0 °C temp_min_days_>0
<= 2 °C temp_min_days_<=2
<= 0 °C temp_min_days_<=0
< -2 °C temp_min_days_<-2
< -10 °C temp_min_days_<-10
< -20 °C temp_min_days_<-20
< - 30 °C temp_min_days_<-30

Days With Rainfall

ECCC_name weathercan_name
>= 0.2 mm rain_days_>=0.2
>= 5 mm rain_days_>=5
>= 10 mm rain_days_>=10
>= 25 mm rain_days_>=25

Days With Snowfall

ECCC_name weathercan_name
>= 0.2 cm snow_days_>=0.2
>= 5 cm snow_days_>=5
>= 10 cm snow_days_>=10
>= 25 cm snow_days_>=25

Days With Precipitation

ECCC_name weathercan_name
>= 0.2 mm precip_days_>=0.2
>= 5 mm precip_days_>=5
>= 10 mm precip_days_>=10
>= 25 mm precip_days_>=25

Days With Snow Depth

ECCC_name weathercan_name
>= 1 cm snow_depth_days_>=1
>= 5 cm snow_depth_days_>=5
>= 10 cm snow_depth_days_>=10
>= 20 cm snow_depth_days_>=20


ECCC_name weathercan_name
Speed (km/h) wind_speed
Most Frequent Direction wind_dir
Maximum Hourly Speed (km/h) wind_max_speed
Date (YYYY/DD) wind_max_speed_date
Direction Of Maximum Hourly Speed wind_max_speed_dir
Maximum Gust Speed (km/h) wind_max_gust
Date (YYYY/DD) wind_max_gust_date
Direction Of Maximum Gust wind_max_gust_dir
Days With Winds >= 52 km/h wind_days_>=52
Days With Winds >= 63 km/h wind_days_>=63

Degree Days

ECCC_name weathercan_name
Above 24 °C dd_above_24
Above 18 °C dd_above_18
Above 15 °C dd_above_15
Above 10 °C dd_above_10
Above 5 °C dd_above_5
Above 0 °C dd_above_0
Below 0 °C dd_below_0
Below 5 °C dd_below_5
Below 10 °C dd_below_10
Below 15 °C dd_below_15
Below 18 °C dd_below_18

Soil Temperature

ECCC_name weathercan_name
At 5 cm Depth (AM Obs) (°C) soil_temp_am_5
At 5 cm Depth (PM Obs) (°C) soil_temp_pm_5
At 10 cm Depth (AM Obs) (°C) soil_temp_am_10
At 10 cm Depth (PM Obs) (°C) soil_temp_pm_10
At 20 cm Depth (AM Obs) (°C) soil_temp_am_20
At 20 cm Depth (PM Obs) (°C) soil_temp_pm_20
At 50 cm Depth (AM Obs) (°C) soil_temp_am_50
At 50 cm Depth (PM Obs) (°C) soil_temp_pm_50
At 100 cm Depth (AM Obs) (°C) soil_temp_am_100
At 100 cm Depth (PM Obs) (°C) soil_temp_pm_100
At 150 cm Depth (AM Obs) (°C) soil_temp_am_150
At 150 cm Depth (PM Obs) (°C) soil_temp_pm_150
At 300 cm Depth (AM Obs) (°C) soil_temp_am_300
At 300 cm Depth (PM Obs) (°C) soil_temp_pm_300


ECCC_name weathercan_name
Lake Evaporation (mm) lake_evaporation

Bright Sunshine

ECCC_name weathercan_name
Total Hours sun_hours
Days With Measurable sun_measurable_days
% Of Possible Daylight Hours sun_perc_daylight_hours
Extreme Daily sun_extreme_daily
Date (YYYY/DD) sun_extreme_daily_date


ECCC_name weathercan_name
Extreme Humidex hmdx_extreme
Date (YYYY/DD) hmdx_extreme_date
Days With Humidex >= 30 hmdx_days_>=30
Days With Humidex >= 35 hmdx_days_>=35
Days With Humidex >= 40 hmdx_days_>=40

Wind Chill

ECCC_name weathercan_name
Extreme Wind Chill wind_chill_extreme
Date (YYYY/DD) wind_chill_extreme_date
Days With Wind Chill < -20 wind_chill_days_<-20
Days With Wind Chill < -30 wind_chill_days_<-30
Days With Wind Chill < -40 wind_chill_days_<-40


ECCC_name weathercan_name
Average Vapour Pressure (kPa) humidity_mean_pressure
Average Relative Humidity - 0600LST (%) humidity_mean_0600LST
Average Relative Humidity - 1500LST (%) humidity_mean_1500LST


ECCC_name weathercan_name
Average Station Pressure (kPa) pressure_stn_mean
Average Sea Level Pressure (kPa) pressure_sea_mean


ECCC_name weathercan_name
Global - RF1 (MJ/m2) rad_global_rf1
Extreme Global - RF1 (MJ/m2) rad_extreme_global_rf1
Date (YYYY/DD) rad_extreme_global_rf1_date
Diffuse - RF2 (MJ/m2) rad_diffuse_rf2
Extreme Diffuse - RF2 (MJ/m2) rad_extreme_diffuse_rf2
Date (YYYY/DD) rad_extreme_diffuse_rf2_date
Reflected - RF3 (MJ/m2) rad_reflected_rf3
Extreme Reflected - RF3 (MJ/m2) rad_extreme_reflected_rf3
Date (YYYY/DD) rad_extreme_reflected_rf3_date
Net - RF4 (MJ/m2) rad_net_rf4
Extreme Net - RF4 (MJ/m2) rad_extreme_net_rf4
Date (YYYY/DD) rad_extreme_net_rf4_date

Visibility (Hours With)

ECCC_name weathercan_name
< 1 Km visibility_<1
1 To 9 Km visibility_1_9
> 9 Km visibility_>9

Cloud Amount (Hours With)

ECCC_name weathercan_name
0 To 2 Tenths cloud_0_2
3 To 7 Tenths cloud_3_7
8 To 10 Tenths cloud_8_10
Average Date Of Last Spring Frost date_last_spring_frost
Average Date Of First Fall Frost date_first_fall_frost
Average Length Of Frost-Free Period length_frost_free
Probability Of Last Temperature In Spring Of 0 °C Or Lower On Or After Indicated Dates prob_last_spring_temp_below_0_on_date
Probability Of First Temperature In Fall Of 0 °C Or Lower On Or After Indicated Dates prob_first_fall_temp_below_0_on_date
Probability Of Frost-Free Period Equal To Or Less Than Indicated Period (Days) prob_length_frost_free