Land

Climate

The sum total of weather over a period constitutes the climate. It is the net result of various factors, the most important of which are temperature, precipitation, wind, sunshine and clouds. Climate has a profound effect on the economic development of a region. It has also a great bearing on the social and cultural activities of the people.

Seasons

There are three well defined seasons in the Punjab. These are:

1. Hot Season (mid-April to the end of June)

2. Rainy Season ( early July to the end of September)

3. Cold Season (early December to the end of February)

The transitional seasons are:

1. Post-monsoon (September to end of November). It is transitional period between the rainy and cold seasons.

2. Pre-hot season (March  to mid-April). It is a transitional period between the cold and hot seasons.

Hot Season

The temperature begins to rise from February onwards. Though the real hot seasons starts in mid-April, the rising temperature breaks the high pressure belt in the north-west of the Indian peninsula. The atmospheric pressure over this region in February is about 987 milli bars. The minimum is reached in early June when it is near about 970 milli bars.

Rainy Season

This is the most welcome season and the agricultural year starts with its advent. Monsoon winds reach the region normally in the first weeks of July. The Bay of Bengal branch of the monsoon current is the main source of rainfall.

Winter Season

The fall in temperature is minimum in January, when the mean temperature falls to 12^oC during day time and to 5^oC during the night. The winter season, cherished by the affluent, becomes a curse for the poor who cannot afford warm clothing

Post-Monsoon  Transitional Season

Monsoon normally retreat by the middle of September. With this a gradual change in weather takes place and continuous so till the end of November. Thus October and November are the months with transitional climates between rainy and winter seasons. The weather remains generally dry and fair.

Post-Winter  Transitional Season

By early March the winter season begins to fade and by the middle of April, it ultimately emerges as hot season. At times there may be a shower or two accompanied by hail storms and squalls which do a lot of damage to crops.

The winds are warm and dry during the last days of March, it is the time for harvest.

Temperature

The sub-tropical latitudinal and continental location of Punjab makes the variation of temperature from month to month very high. Though the minimum air temperature rarely drops below 0^o C, ground frost is a common phenomenon in mid -winter. The rise in temperature is gradual when the air has high moisture content with the sky remaining overcast; the rise is however steep when the sky is clear and there is little moisture content in the air. 

The highest day time temperature is recorded during the months of May and June. It is  40.4^o C at Patiala, 40.4^o C at Amristar and 41.2^o C at Ludhiana. At Ludhiana the highest maximum temperature on record was 46.1^o C while at Amritsar and Patiala the highest record was 45.5^o C. The daily maximum temperature at Ludhiana remains above 41^o C for 45 days in a year. The lowest maximum temperature is recorded during the month of January . When the sun's rays are more oblique as compared to the other months. The cold winds check the rise of day temperature.

The minimum temperature is lowest from December to February. The lowest minimum temperature recorded at Amristar is 0.2^o C and at Ludhiana 0.5^oC. At Amristar the minimum temperature remain below 5^oC for 55 days. The maximum number of days with the lowest night time temperature are in the month of January. The highest minimum temperature is recorded in the month of June. When it is even higher than the day temperature of December and January. At Ludhiana for 55 days in the year the minimum temperature is as high as 27^o C. The maximum number of days with such  high night temperature are in the month of June. The annual range of temperature all over the state is around 21^oC. The mean monthly range of temperature varies from 9^oC in July to about 18^oC in November.

Rainfall

The amount of rainfall in the Punjab ranges between 250 mm and 1000 mm. The maximum falling near the Shivalik Hills and the minimum towards the desert in  the west. 70 to 80 percent of the total rainfall is concentrated during the three months of south-west monsoon winds and the rest comes during the winter months. There is wide difference in the amount of rainfall experienced in east and west Punjab. Near the hills rainfall is over 1000 mm.  Gurdaspur, Hoshiarpur, Ropar district and eastern parts of Patiala receive an annual rainfall of more than 750 mm. The 500 mm rainfall line runs in a north-west to south-east direction and cuts the Punjab into almost two equal zones. The Fazilka tehsil in the extreme west receive a rainfall of less than 250 mm.

Monsoon Rainfall

The major part of annual rainfall is experienced during the monsoon period, when the monsoon current in the Bay of Bengal enters from the south-east. The normal onset of the monsoon in Punjab is in the first week of July.

Winter Rainfall

During the winter season, weather in Punjab is normally cool and dry. This type of weather is associated with the passage of western disturbances through the region.

The importance of winter rainfall in Punjab is immense primarily because of its time and effectiveness. In the area adjoining the Shivalik Hills, winter crops is dependent upon this rainfall. The sub-Shivalik region receives more than 100 mm of rainfall from December to March.