S.D. Codified Laws § 23A-41-1
In computing any period of time, the day of the act, event, or default from which the designated period of time begins to run shall not be included. The last day of the period so computed shall be included, unless it is a Saturday, a Sunday, or a legal holiday or, when the act to be done is the filing of a paper in court, a day on which weather or other conditions have made the office of the clerk of court inaccessible, in which event the period runs until the end of the next day which is not one of the aforementioned days. When a period of time prescribed or allowed is less than eleven days, intermediate Saturdays, Sundays, and legal holidays shall be excluded in the computation. As used in this section, a "legal holiday" is any day designated as a holiday in § 1-5-1.
SDCL 23A-41-1