Agriculture and Agri-Food Canada

Mean Temperature Difference From Normal values are computed by subtracting the normal monthly average temperature from the average monthly temperature of the month. The average monthly temperature is computed by obtaining the mean value of average daily temperatures for a month. If the month was...

Growing degree days (GDDs) are used to estimate the growth and development of plants and insects during the growing season. Growing Degree Day are computed by subtracting a base value temperature from the mean daily temperature and are assigned a value of zero if negative. Base temperatures are a...

The term "Palmer Drought Index" has been used collectively to represent multiple indices. This index is simply a water balance model which analyzes precipitation and temperature, and used as a tool to measure meteorological and hydrological drought across space and time. All versions of the...

Crop Heat Units (CHU) are calculated on a daily basis, using the maximum and minimum temperatures in order to account for a crop’s negative response to higher temperatures. The formula used to calculate the CHU value for a day is: (1.8 × (Minimum Temperature − 4.4) + 3.33 × (Maximum...

Percent of normal soil moisture is the modelled amount of plant available water (mm) in the root zone of the soil, divided by the average amount that has historically been available on that day. This value is intended to provide users with a representation of conditions above or below normal as a...

Difference from normal soil moisture is the modelled amount of plant available water (mm) in the root zone of the soil, minus the average amount that has historically been available on that day. This value is intended to provide users with a representation of conditions above or below normal and...

Total soil moisture is the modelled amount of plant available water (mm) in the root zone of the soil. The value given is the amount calculated to be present on the modeled day of the product. Values are computed using the Versatile Soil Moisture Budget (VSMB)

The Blended Index (BI) is a model which employs multiple potential indicators of drought and excess moisture, such as the Palmer drought index, rolling precipitation amounts and soil moisture, and combines them into a weighted, normalized value between 0 and 100. The inputs and weights used in...

The term "Palmer Drought Index" has been used collectively to represent multiple indices. This index is simply a water balance model which analyzes precipitation and temperature, and used as a tool to measure meteorological and hydrological drought across space and time. All versions of the...

The Moisture Anomaly Index (Palmer-Z) is an estimate of the moisture difference from normal (a 30-year mean). It attempts to express conditions for the current month regardless of what may have occurred before the month in question.

Percent of Average Precipitation represents the accumulation of precipitation for a location, divided by the long term average value. The long term average value is defined as the average amount over the 1981 – 2010 period. Products are produced for the following timeframes: Agricultural Year,...

The Standardized Precipitation Index (SPI) has been recognized as the most accessible index for quantifying and reporting meteorological drought. On short timescales, the SPI is closely related to soil moisture, while at longer timescales, the SPI can be related to groundwater and reservoir...

The Blended Index (BI) is a model which employs multiple potential indicators of drought and excess moisture, such as the Palmer drought index, rolling precipitation amounts and soil moisture, and combines them into a weighted, normalized value between 0 and 100. The inputs and weights used in...

The Standardized Precipitation Evapotranspiration Index (SPEI) is computed similarly to the SPI. The main difference is that SPI assesses precipitation variance, while SPEI also considers demand from evapotranspiration which is subtracted from any precipitation accumulation prior to assessment....

Dry spell periods are defined as the number of days (April 1 – October 31) where daily precipitation is less than 0.5 mm. This is not an accumulation of precipitation, simply a count of days. Dry spell products are only generated during the Growing Season, April 1 through October 31.

Minimum Temperature represents the lowest recorded temperature value (°C) at each location for a given time period. Time periods include the previous 24 hours and the previous 7 days from the available date where a climate day starts at 0600UTC.

Maximum Temperature represents the highest recorded temperature value (°C) at each location for a given time period. Time periods include the previous 24 hours and the previous 7 days from the available date where a climate day starts at 0600UTC.

Precipitation Percentiles represents the accumulated precipitation (mm) for the time period compared to historical information for the same time period. This comparison ranks the current precipitation amount and assigns it a percentile value based on a historic record. Products are produced for...

Heat Wave represents the consecutive number of days (April 1 – October 31) where the maximum daily temperature is greater than 25 or 30 degrees respectively. Heat wave products are only generated during the Growing Season, April 1 through October 31.

The Versatile Soil Moisture Budget (VSMB) is a soil water budget model that is continuous and deterministic in nature and was developed by AAFC. It is based on the premise that the water available for plant growth is gained by precipitation or irrigation, and lost through evapotranspiration and...