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Around the House: West Guilford, ON

Current Weather Updated: Sun. Aug 20, 2017, 5:28 EDT -






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Also known as maximum temperature. The highest air temperature attained during a specific time interval, usually 24 hours.

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20°C 20°C 21°C

Wind is the horizontal movement of air in relation to the earth's surface. Wind direction tells where the wind is blowing from. For example, a "north wind" is coming from the north and is blowing towards the south. There are four components of wind that are measured: direction, speed, character (i.e. whether it's a gust or a squall) and shifts.

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8km/h 7km/h 18km/h

P.O.P. stands for "Probability of Precipitation." It does not predict when, where or how much precipitation will occur. When a weather service issues a forecast calling for rain, it is usually followed by a probability.

For example: "P.O.P. 60%." This expression means there is a 60% chance that any random place in the forecast area, such as your home, will receive measurable rainfall. Measurable rainfall means at least 0.2 mm of rain or the water equivalent of snow.

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20% 20% 20%

Heating and Cooling Your Home

Heating degree-days and cooling degree-days are used primarily to estimate the heating and cooling requirements of buildings.

The white line on the graph represents the normal number of heating degree days for each day in the 14-day period. The yellow line on the graph represents the forecasted number of heating degree days for each day in the 14-day period.

When the yellow line is above the white line you may see an increase in your heating bill as a result of cold temperatures. When the yellow line is at or below the white line your heating bill will likely be normal or slightly cheaper.

More about heating degree days...

The amount of energy needed to heat a home for a year depends on how many cold days there are in the year and on how cold it gets on each of those days. When the weather is slightly cool, a little bit of heat might be needed for a few hours in the evening or early morning to stay comfortable. On a very cold day, a lot of heat will be needed all day and all night. A day's average temperature gives some idea of how much heat will be needed on that day.

Climatologists use a measurement known as heating degree-days (HDDs) to estimate heating needs more precisely. They assume that people will use at least some heat on any day that has an average outdoor temperature of less than 18°C. They then calculate the heating needs for each day by subtracting the day's average temperature from 18. The result is the number of heating degrees for that day or HDDs.

Cooling requirements, known as cooling degree-days or CDDs, can be measured in much the same way. The assumption this time is that there is some need for cooling on days when the average temperature is above 18°C. Subtracting 18 from the day's average temperature thus gives the number of cooling degrees for that day or CDDs.

When the heating or cooling degrees for each day are added up for a season or year, the result is a very useful statistic that indicates how much demand there is for heating or cooling as a result of different climate conditions. The amount of energy actually needed to heat or cool a particular building will, of course, depend on many other factors, such as how well the building is insulated and the temperature that it is kept at.

Heating degree-days in Canada vary from about 3,000 a year in balmy Victoria to about 13,000 in the Far North. Over the past century, HDDs have declined significantly in most of Canada. Cooling degree-days range as high as 400 per year in the Windsor area of southwestern Ontario but average fewer than 100 in many parts of the country. Increases in cooling degree-days have been smaller and less widespread than the decreases in heating degree-days.

In cities, these trends may also be affected by what is known as the heat island effect. City surfaces, like roads, buildings, and rooftops, absorb large amounts of heat from the sun during the day and then release it at night as they cool. As a result, temperatures within a city, especially a densely built downtown core, are often noticeably warmer than temperatures recorded on the city's outskirts. As a city grows, the heat island effect grows with it. Consequently, heating needs can decrease and cooling needs increase simply because a place is becoming more urbanized.

Information courtesy of Canadian Council of Ministers of the Environment.

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