Simple prototype for weather notifications based on the Yahoo! weather API. Needs support for multiple locations and a way for people to subscribe.

weather_notifications.py

#!/usr/bin/env python3
# coding: utf-8

import yweather
import shelve
import datetime
from conditions import conditions

def send_plain_mail(subject, body, from_mail, to):
    import smtplib
    from email.mime.text import MIMEText
    from email.encoders import encode_quopri
 
    msg = MIMEText(body, 'plain', 'iso-8859-1')
 
    msg['Subject'] = subject
    msg['From'] = from_mail
    msg['To'] = to
 
    s = smtplib.SMTP()
    s.connect()
    s.sendmail(from_mail, [to], msg.as_string())
    s.close()

def recent(history,key="code",n=5):
    if key == "code":
        return [conditions[day[key]] for day in sorted(history.values(),key = lambda e:e["timestamp"])[-n:]]
    else:
        return [float(day[key]) for day in sorted(history.values(),key = lambda e:e["timestamp"])[-n:]]

def rain_test(history,forecast):
    past_conditions = recent(history)
    f_condition = conditions[forecast["code"]]
    if "good" not in past_conditions and f_condition == "good":
        return "good_alert"
    elif "bad" not in past_conditions  and f_condition == "bad":
        return "bad_alert"

def temperature_test(history,forecast):
    delta = 3
    past_high = recent(history,"high")
    f_high = float(forecast["high"])
    past_low = recent(history,"low")
    f_low = float(forecast["low"])
    if f_high >= max(past_high) + delta:
        return "high_temp_alert"
    if f_low <= min(past_low) - delta:
        return "low_temp_alert"

alert_subjects = {"good_alert": "Belle journée en perspective!",
                  "bad_alert":  "Prends ton parapluie!",
                  "high_temp_alert": "Il va faire chaud!",
                  "low_temp_alert":  "Attention, il va faire frisquet!"}

subscribers = ["test@example.com"]


if __name__ == '__main__':
    data = shelve.open("history.db")
    c = yweather.Client()
    woeid = c.fetch_woeid("Springfield, NY")
    weather = c.fetch_weather(woeid,metric=True)
    today = weather["forecast"][0]
    today["timestamp"]=datetime.datetime.now()
    data[today["date"]] = today
    tests = [rain_test,temperature_test]
    for test in tests:
        alert = test(data,weather["forecast"][1])
        if alert:
            for email in subscribers:
                send_plain_mail(alert_subjects[alert],"http://fr.meteo.yahoo.com/place/","sender@example.com",email)
            print("Alert sent!")
            break # don't send a thousand alerts on the same day