temp_mean = data["temperature"].mean() 
temp_std = data["temperature"].std()

data["mean"] = temp_mean
data["upper_limit"] = temp_mean + (temp_std * 3)
data["lower_limit"] = temp_mean - (temp_std * 3) 

print(data.iloc[0]["upper_limit"])
print(data.iloc[0]["mean"])
print(data.iloc[0]["lower_limit"])

29.513933116002725
14.5345
-0.44493311600272456