Siobhan is a moderately popular girls' name in England & Wales, ranking #209 in 1999 with 201 recorded births. The name reached its all-time peak in 1996 with 332 births ranking #138. Since 1996, the popularity has decreased by 39.5%. In 1999, approximately 1 in every 1,401 girls born was named Siobhan. STABLE Recent data shows the name is currently stable.