I'll assume your data is on file as you suggested in your comment. Then:
data = ReadList["datas.txt", Word, RecordLists -> True] Gives
{{"YEAR", "JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC"}, {"1950", "-1.022", "-1.146", "-1.289", "-1.058", "-1.419", "-1.36", "-1.334", "-1.05", "-0.578", "-0.395", "-1.151", "-1.248"}, {"1951", "-1.068", "-1.196", "-1.208", "-0.437", "-0.273", "0.48", "0.747", "0.858", "0.776", "0.75", "0.729", "0.466"}, {"1952", "0.406", "0.131", "0.086", "0.262", "-0.267", "-0.634", "-0.231", "-0.156", "0.362", "0.309", "-0.34", "-0.124"}, {"1953", "0.024", "0.379", "0.263", "0.712", "0.84", "0.241", "0.416", "0.253", "0.524", "0.092", "0.049", "0.314"}} Now, very crude, but I had to approach this differently from kale's elegant method:
pl = Table[{StringJoin[data[[1, #]], " ", data[[k, 1]]], ToExpression[data[[k, #]]]} & /@ Range[2, 13], {k, 2, Length@data}] Finally,
DateListPlot[pl, Joined -> True]