Cyclone Warning

The Class System of Warnings is based primarily on the extent of the risk and secondly on the time factor. The coded Class System by itself can, in no way, indicate the intensity or size of the cyclone nor the extent to which gusts will exceed 120 km/h.

​CLASS I ​Issued 36-48 hours before Mauritius or Rodrigues is likely to be affected by gusts reaching 120 km/h.
​CLASS II Issued to allow, as far as practicable 12 hours of daylight before the occurrence of gusts of 120 km/h.
CLASS  III                    
​Issued to allow, as far as practicable, 6 hours of daylight before the advent of 120 km/h gusts.
​     CLASS IV      
Issued when gusts of 120 km/h have been recorded in some places and are expected to continue.
​TERMINATION​Issued when there is no longer any risk of gusts exceeding 120 km/h.

The threshold of 120 km/h represents the speed at which significant damages may start to occur to trees and structures. 

Code Flags Flown on Certain Buildings are as Follows:-  

Warning Class I - One red flag 

Warning Class II - Two red flags 

Warning Class III - Three red flags  

Warning Class IV - Three red flags

Termination  - One blue flag

Cyclone Bulletins 

(i) Cyclone Bulletins are issued by the MMS and give the position, intensity and movement of a cyclone with a forecast of the expected changes in the conditions of the wind, rain and the sea, expected time of commencement of specified wind speed and gust conditions.  Advice about precautions are given in general terms but all recipients must necessarily apply the contents of the forecast to their own situation because, for instance, a householder may be able to close his shutters in a few minutes during the night whereas the proper protection of fishing boats require a considerable period of daylight hours. 

(ii) Cyclone Bulletins numbering from a few to a dozen or more for each cyclone are issued at generally at 6-hourly intervals or more often. Each bulletin is labelled first, second, third, etc, and dated and timed. Each shall also state the time when the next bulletin will be issued.
(iii) The bulletins will contain, as detailed above, a description of the cyclone and efforts will be made to keep them fairly concise and to avoid verbosity. They will normally be issued at twelve (12) hourly intervals for Cyclone Warning Class I and six (6) hourly intervals for Class II but when the cyclone is very near, the frequency will be increased to three (3) hourly intervals for Cyclone Warning Class. New observation sometimes necessitates a revision of the outlook or even of the past history. An upgrading or a downgrading of the warning status may have to be made unexpectedly. The MMS will issue warning appropriate to the prevailing meteorological situation and outlook without regard to any rules which transport or business enterprises have laid down for their own conduct in a cyclone warning situation.

(iv) Special attention need to be given for the issue of possible warnings to the public and tourist community to ensure that the calm period during the passing of the eye of the cyclone is not mistaken for an end of the cyclonic winds. 

(v) As far as possible, a line of communication between the MMS, the NDRRMC, the MBC and the private radios will be maintained at all times.  The public should be made aware of the possibility of an interruption in the flow of information.  It should be understood that precautions should have been taken prior to the advent of cyclonic conditions. 

(vi) At the beginning of holiday periods or week-ends, advance issue of a warning may be found necessary to allow preliminary precautions to be taken and making arrangements for personnel to be made available for more elaborate precautions.

Distribution of Cyclone Warning Bulletins 

Cyclone information is disseminated through the MBC, NDRRMC, Police, Public & Private Radio Stations, the Press and the Audiotex and Telmet Services.  This scheme provides general responsibilities and actions of: 
(a) All organisations;
(b) Alerting agency;
(c) Coordinating agencies at National and Municipal/Districts Council levels;
(d) Main response agencies, and
(e) Other stakeholders. 

The scheme is divided under the following sections:
(a) General Preparedness before Cyclonic Season;
(b) Upon Approach of cyclone; 
(c) During cyclone, and
(d) Aftermath.

Please click here for more information on Cyclone Warnings