I don't get it.

Ralen said:
I don't get it.

Now they can hold hands

Krugger said:
Now they can hold hands

Ohhhh

Cute

1. Kyon's shirt is pretty ZU~N! I bet he likes love sign's illusion laser, making haruhi feel it so much that #2 applies
2. I think it's quite likely that it's done so that Kyon doesn't have to endure it alone, as a parasol is a pretty crappy cover for two. As an added bonus they get to hold hands?
Thinking about it it's quite likely as kyon never mentioned anything about the heat before noticing/commenting on the parasol.
Knowing kyon's demeanor it could have been sarcastic and Haruhi read the mood, and picked up on it?

How very considerate of her. Truly, connubial bliss has changed Haruhi.

Attempt 1: sharing a parasol- failed
Attempt 2: holding hands - success!

And you MUST hold onto a parasol with both hands...?

MisterFox said:
And you MUST hold onto a parasol with both hands...?

The tip of her parasol is at line with Kyon's eye. You can think of possible accident yourself. Holding it sideways might defeat the purpose of blocking her entire body out from sun rays.