I read somewhere that you should do extra watering of lawn (after sunset), if the temperature exceeded 80° F during the day.
So, a really quick hack works like this:
A bash script
#!/bin/bash
TEMP="`/usr/bin/mysql -ss open2300 -e \"SELECT
FLOOR(MAX(temp_out)) FROM weather GROUP BY (rec_date) ORDER BY
rec_date DESC LIMIT 1;\"`"
if [ "$TEMP" -ge 80 ]; then
/root/water-on.exp
/root/water2.exp 120 1
/root/water3.exp 120 1
fi