The members of the city council, at their first meeting each calendar year and thereafter whenever a vacancy occurs in the office of mayor pro tempore, shall elect from among their number a mayor pro tempore, who shall hold office at the pleasure of the council and in case of the absence of the mayor, perform the duties of mayor except that he or she shall not have the power to appoint or remove any officer or to veto any ordinance.
The mayor and the mayor pro tempore shall have power to administer oaths and affirmations, take affidavits and certify them. The mayor or the mayor pro tempore when acting as mayor, shall sign all conveyances made by the city and all instruments which require the seal of the city.
RCW 35.23.191