September weather forecastRajbiraj, Nepal
September
Weather in September
September marks the decline of monsoon and ushers in a transition towards the drier part of the year. The substantial decrease in the amount of rainfall to 141mm (5.55"), combined with longer sunshine hours, signals the withdrawal of monsoon season. With the highest temperature dropping to 33.1°C (91.6°F), it carries the existing monsoon remains while preparing for the forthcoming autumn season. The diminishing cloud coverage and steadying of wind speed at around 10km/h (6.2mph), further underpin this seasonal transition. The Septembers offer travelers a solacing retreat, with the perfect mingling of clear skies and minimal showers.Temperature
The initiation of September sees an average high-temperature of a still tropical 33.1°C (91.6°F), showing minor variations from the previous month. Rajbiraj in September anticipates an average nighttime temperature of 25.6°C (78.1°F).Heat index
The heat index in September is estimated at a blazing hot 45°C (113°F). Remain cautious: Heat cramps along with heat exhaustion are foreseeable. Ongoing activity may precipitate heatstroke.The standards for the heat index are set for locations in shade and under light breezes. Being under direct sunlight might amplify the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'apparent temperature', is found by incorporating humidity levels into the air temperature measurement. Physical activity, clothing, and metabolic variations are additional factors that impact an individual's perception of temperature. Recognize that direct exposure to the sun can escalate the heat effect, potentially adding 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values are especially crucial for babies and toddlers. In general, younger individuals are at greater risk than adults because they tend to sweat less. Also, having a larger skin surface to body size ratio and greater heat production due to their active behavior contribute to this danger.
One of the main methods the human body employs to cool down is by perspiring, as this process allows sweat to evaporate and remove excess heat. Higher relative humidity impedes evaporation, thus reducing heat dispersion from the body, culminating in a sensation of overheating. If heat absorption exceeds the body's cooling ability, body temperature can elevate, resulting in potential thermal illnesses.
Humidity
The months with the highest humidity are July and September, with an average relative humidity of 73%.Rainfall
In Rajbiraj, in September, during 21.5 rainfall days, 141mm (5.55") of precipitation is typically accumulated. In Rajbiraj, during the entire year, the rain falls for 131.9 days and collects up to 787mm (30.98") of precipitation.Daylight
The average length of the day in September in Rajbiraj is 12h and 19min.On the first day of September, sunrise is at 5:37 am and sunset at 6:17 pm. On the last day of the month, sunrise is at 5:50 am and sunset at 5:45 pm +0545.
Sunshine
In September, the average sunshine is 8.5h.UV index
In September, the average daily maximum UV index is 7. A UV Index value of 6 to 7 symbolizes a high health vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.Note: A daily high UV index of 7 in September leads to these guidelines:
Act on precautions and pay attention to sun safety recommendations. Avoidance of sunburn is obligatory. Limit your direct sun exposure, especially between 10 a.m. and 4 p.m., when UV radiation is strongest. Shade structures might not provide complete sun protection. Boost your sun resistance with garments that are densely woven yet spacious.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Rajbiraj, Nepal
- Average high temperature in September: 33.1°C
The warmest month (with the highest average high temperature) is May (38.3°C).
The month with the lowest average high temperature is January (23.7°C).
- Average low temperature in September: 25.6°C
The month with the highest average low temperature is June (28°C).
The coldest month (with the lowest average low temperature) is January (12.4°C).
Average pressure in September
Rajbiraj, Nepal
- Average pressure in September: 1005.2mbar
The month with the highest atmospheric pressure is January (1015.9mbar).
The month with the lowest atmospheric pressure is June (1000mbar).
Average wind speed in September
Rajbiraj, Nepal
- Average wind speed in September: 10km/h
The windiest month (with the highest average wind speed) is May (14.3km/h).
The calmest month (with the lowest average wind speed) is November (7.6km/h).
Average humidity in September
Rajbiraj, Nepal
- Average humidity in September: 73%
The months with the highest relative humidity are July and September (73%).
The month with the lowest relative humidity is March (33%).
Average rainfall in September
Rajbiraj, Nepal
- Average rainfall in September: 141mm
The wettest month (with the highest rainfall) is July (246mm).
The driest months (with the least rainfall) are November and December (2mm).
Average rainfall days in September
Rajbiraj, Nepal
- Average rainfall days in September: 21.5 days
The month with the highest number of rainy days is July (25.2 days).
The months with the least rainy days are November and December (1.5 days).
Average daylight in September /
Average sunshine in September
Rajbiraj, Nepal
- Average daylight in September: 12h and 18min
The month with the longest days is June (Average daylight: 13h and 48min).
The month with the shortest days is December (Average daylight: 10h and 30min).
- Average sunshine in September: 8h and 30min
The months with the most sunshine are April and May (Average sunshine: 11h and 42min).
The month with the least sunshine is January (Average sunshine: 7h and 24min).
Average sunshine days in September
Rajbiraj, Nepal
- Average sunshine days in September: 6.9 days
The month with the most sunshine days is December (29.2 days).
The month with the least sunshine days is July (4.3 days).
Average UV index in September
Rajbiraj, Nepal
- Average UV index in September: 7
The months with the highest UV index are April and May (UV index 8).
The months with the lowest UV index are January and December (UV index 5).
Average cloud cover in September
Rajbiraj, Nepal
- Average cloud cover in September: 38
The month with the most cloud cover is July (Cloud cover 51).
The month with the least cloud cover is November (Cloud cover 7).
Average visibility in September
Rajbiraj, Nepal
- Average visibility in September: 9km
The months with the highest visibility are January, February, March, April, May, June, October, November and December (10km).
The months with the lowest visibility are July, August and September (9km).





