Thing speak is free website to plot your datas.you can easily plot the data using following simple python code. here key is different for all account holders. so please change the key before you run.
CODE
from pprint import pprint
import requests
r = requests.get('https://api.thingspeak.com/update?api_key=TJUR27NUM08GYBD0&field1=30')
pprint(r.json())
or
from pprint import pprint
import requests
requests.get('https://api.thingspeak.com/update?api_key=TJUR27NUM08GYBD0&field3=50')