Pestilential, Houston's pestilential
Pestilential, especially in July

Pestilential in July 
It's so hot that birds won't fly 

In July ... birds won't fly 
... oh ... oh ... oh ... oh

Pestilential, Houston's pestilential 
Pestilential, especially in July

Pestilential in July 
Bugs so big that they can fly 

In July ... bugs can fly
oh ... oh ... oh ... oh

Pestilential, Houston's pestilential 
Pestilential, especially in July

From the OED

1. Producing or tending to produce pestilence or epidemic;
noxious to life  or health; 

1727 What passed in London Wks. 1755 III I. 187 A pestilential
malignancy in  the air, occasioned by the comet. 

1796 The Campagna di Roma..is now almost pestilential. 

1882 In the sultry pestilential mists of a summer day in Maremma. > > >

2. Of the nature of or pertaining to
pestilence or infectious and  deadly disease; 
spec. of the nature of or
pertaining to bubonic plague.

1530  a carboncle, a sore pestylenciall

1548 In this sommer, the Pestilenciall plage..infected the Citie of
London > and the countrei round about.

1790 This may be called the pestilential fever of Europe, as in many
of its symptoms it bears a great resemblance to that dreadful disease the >
plague. 

1885 There's the pestilential nuisances who write for 
autographs... they'd none of 'em be missed!

1911 A sneeze may still mean the onset of a
pestilential cold in the  head

1982 The Militant Tendency is undoubtedly an infiltrationist group 
which has quite different aims from  the bulk of the Labour Party. 
Mr Foot described it some time ago as a pestilential nuisance.