S.D. Codified Laws § 15-6-6(a)
In computing any period of time prescribed or allowed by this chapter, by order of court, or by any applicable statute, 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 the 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 rule, "legal holiday" includes those holidays listed in § 1-5-1.
Service by facsimile, electronic mail transmission, and through the Odyssey® electronic filing system must be completed by 11:59 p.m. central standard time or daylight savings time as applicable, on a weekday, which is not a legal holiday, or service shall be deemed to be made on the following weekday, which is not a legal holiday.
SDCL 15-6-6(a)