An Air Carrier Captain expressed frustration at his carrier for not loading enough contingency fuel for weather delays and consequently he declared a fuel emergency to divert after his destination airport was closed for thunderstorms.

Narrative

As we approached our destination; thunderstorms were developing in the area. Houston Center was vectoring us to the east to get around the storms. Eventually Houston Center gave us a new clearance to our destination then to an arrival from the south. (Don't have that arrival in front of me). The new clearance was too great a distance to fly the entire arrival due the fuel we had at the time. This was about 5;000 LBS. We ask Center numerous times that we need to start heading to our destination quickly as our fuel was getting low. Eventually we got vectored to the airport with about 3;800 LBS. At that time our destination went into holding due to the thunderstorms over the field. We immediately turned toward the closest airport and our fuel indication showed 2;000 LBS on landing. I declared a Fuel Emergency with that fuel indication. Houston Center and Approach were very helpful getting us vectored and landing. [We] landed with 2;300 LBS of fuel. My main frustration is that there were thunderstorms forecast for the area. But we now only have 500 LBS contingency fuel. There was no alternate; no extra fuel; no higher contingency fuel added due to the thunderstorms in the area. That left us very little if any options when this kind of stuff happens. When there are storms forecast to be in the area; there should be some extra fuel added for just these types of occurrences.