Weather Information Tidal information: Visakhapatnam has semi diurnal tides. The tidal levels as per naval hydro graphic chart no. 3012 are as follows:
|Highest high water recorded||+ 2.38 m|
|Mhws||+ 1.50 m|
|Mhwn||+ 1.10 m|
|M.s.l.||+ 0.80 m|
|M.l.w.n.||+ 0.50 m|
|M.l.w.s||+ 0.10 m|
|Lowest low water recorded||- 0.55 m|
The above levels are with respect to chart datum. The chart datum at Visakhapatnam is 0.8 m below mean sea level.
- The north east monsoon period is from end November to end February with predominantly north easterly winds.
- The pre-monsoon period is from march to may usually, the period of the year when the winds shift towards south westerly direction.
- The south-west monsoon is from middle of may up to middle of October with predominantly south-westerly winds and cloudy weather and the rainy season.
- The post monsoon is from middle of October to end November with variable weather.
In the bay of Bengal, depressions are likely to be encountered during all seasons of the year with a local fall in the pressure. On an average 4 to 5 cyclones per annum may occur. Cyclones are frequent during the month of November. Cyclones are also likely to occur during the month of may.
From February to June, off shore current flow towards north east. From august to December, currents flow towards south-west. The velocity ranges from 0.5 to 1.0 knot. At Visakhapatnam coast, currents are neither related to wind or to tides in any appreciable way. The determining factor for the direction of current is the direction of predominant wave.
- Deep water waves: the predominant direction of waves during April to September (south west monsoon period) is south-west whereas, during the period from November to February (north-east monsoon period), the predominant direction is north east. The months of march and October are transition periods with no definite predominant direction for the wave approach. Highest wave occurred during April to September. The deep-sea waves with highest and lowest periods frequent from south-west quadrant. Waves of over 1.5 mts. Height may be expected for 20% of the time. Wave periods of over 7 seconds may be expected 14 % of the time.
- Shallow water waves: from march to October principal wave direction is predominantly from south-south-east. The predominant wave period is between 8 to 10 seconds. During the remainder of the year, wave direction is principally from the east and practically all wave directions are confined to the sector between east-north-east and south-east.
The mean daily maximum and minimum temperatures are about 31 c and 23.5 c respectively.
The humidity is comparatively high and fairly uniform during the year. The mean daily relative humidity over a year is about 76% at 0800 hours and 72% at 1700 hrs.
The wet season at Visakhapatnam persists mainly during the south-west monsoon and slightly before and after his period. September and October are the wettest months of the year with the average rain fall of about 170 mm. And 260 mm. Respectively. The average annual rainfall is around 975 mm. The average number of rainy days per annum is 50.
The visibility is good throughout the year, as fog is infrequent at sea in all seasons. The highest monthly average duration recorded fog is 0.1 day in some months from December to may.
Sea Water Salinity
The sea water salinity at Visakhapatnam coat varies from a mean of about 25 c January to 29 c in October.
The salinity varies from a mean of 24.4 % in November to a mean of 34.2% in April.