[IOTL] The (British-made) radar installation operating at Opana Point detected the incoming Japanese aircraft at least one hour before the first strike hit the island.
For some reason, this vital information was never acted upon - even if it reached higher command [This is disputed].
IOTL, some twenty American fighters got into the air to secure six kills and damaged other Japanese bombers (although most of the twenty were themselves shot down).
The relative strengths of the combatants were that the defenders had about 390 aircraft and their attackers some 415.
It seems reasonable that, had the Americans heeded the radar warning and scrambled everything that could fly by (say) even as little as fifteen minutes before the attack then they could have caused significant damage to the Japanese air group. Note that the Japanese first wave of 183 aircraft would have been outnumbered by more than two-to-one.
No doubt it would have been a Phyrric victory: the inexperienced Americans might have lost 50-60% of their aircraft; however, combined with the loss of surprise - so that the harbour attack was againt fully alerted AA defences - a credible suggestion for Japaneses first-wave losses could have been 70% or worse.
Given this scenario, it is perhaps debatable that the Japanese would then have committed the second-wave of 171 aircraft: considering their losses and realising they had failed to achieve surprise they might have then expected a countersrike on their carriers and therefore simply recovered their aircraft and withdrawn.
Even so, whilst the Japanese take heavier losses (than IOTL), the Americans are still going to suffer the same level of damage as OTL records...the Japanese would, after all, press home their attack to the death, as always!
Ultimately, I cannot see the effect on history being much different from what actually happened; it still ends at Hiroshima and Nagasaki.
Assuming he JapanesIt seems reasonable Had the Americans scrambled hour before the planes arrived over the harborattack 1 hour before the planes arrived over the harbor
Not quite sure where your aircraft informations came from, but actual USAAF deployment in Hawaii on 12/7/41 is generally accepted as being
At Bellows
6 North American O-47B observation plane
2 Stinson O-49 Vigilant L-1 observation plane
Two P-40s
At Hickam
33 Douglas B-18 Bolo
12 Boeing B-17D
13 Douglas A-20A Havoc
2 Douglas C-33 (DC-2)
At Wheeler
6 Boeing P-26A Peashooter
6 Boeing P-26B Peashooter
39 Curtiss P-36A Mohawk
87 Curtiss P-40B Tomahawk
11 Curtiss P-40C Kittyhawk
3 Martin B-12
3 Grumman OAF-9 Goose
2 Douglas BT-2
2 North American AT-6 Texan
1 Seversky AT-12A Guardsman
At Haleiwa (not attacked by the Japanese)
2 Curtiss P-36 Mohawk pursuit
8 Curtiss P-40 Kittyhawk pursuit
The total is 223 USAAF aircraft. Fighters 87 P-40B, 19 P-40C, 41 P-36 for a total of 147 pursuit planes (the 12 P-26 can not be counted as actual fighters, although there would undoubted have been some brave fool who would have taken off in them if the opprotunity presented itself). Note that this is a total number, it does not account for the number of planes that were not operational on that Sunday morning. Based on normal peacetime availability you can take between 20 & 30% of the total off the top. It is also important to note that the vast majority of these aircraft were not fully fueled or armed. It is unlikely that more than 70 aircraft could get airborne in under an hour (a LOT of the pilots and ground crew would still be half in the bag from Saturday night, although bombs tend to sober you up PDQ)
Interestingly, Navy aircraft numbers were very low, partly due to the ferry missions to Wake, Midway and elsewhere, but also partly because the USN was in the middle of swapping out the F2A (aka Markus' favorite

) for the F4F-3.
USN/USMC numbers were:
At Ewa Marine Corp Air Station
11 Grumman F4F-3 Wildcat
8 Vought SB2U-3 Vindicator
20 Douglas SBD-1 Dauntless
3 Douglas SBD-2 Dauntless
2 Grumman J2F-4 Duck
1 Lockheed JO-2 Electra Junior
1 Sikorsky JRS-1
2 Douglas R3D-2 (DC-5) 2
1 North American SNJ-3
At Puunene (Lahaina Roads) NAS
4 Beech JRB
4 Northrop BT-1
1 Grumman JRF Goose,
1 Grumman J2F Duck
At Kaneohe NAS
1 Vought OS2U Kingfisher amphibian
36 Consolidated PBY-5 Catalina
At Pearl Harbor (Ford Island) NAS
19 Grumman J2F Duck single engine utility amphibian
9 Sikorsky JRS 18 passenger amphibian flying boat
2 Consolidated PBY-1 Catalina patrol bomber, flying boat, 1936
15 Consolidated PBY-3 Catalina scout bomber, flying boat, 1937
18 Consolidated PBY-5 Catalina
8 Brewster F2A-3 Buffalo fighter, 1939
5 Grumman F4F-3 Wildcat fighter, 1940
5 Grumman F4F-3A Wildcat fighter, 1941
3 Douglas SBD-2 Dauntless scout/dive-bomber, 1941
The total available USN/USMC is also a little deceiving. Most of the USN carrier aircraft had been off loaded from their carriers because they were non Operational and were in pieces as were a number of the Marine aircraft. A lot of the PBY were also "just passing through" with their crews getting a bit of rest before flying on to other locations (these were some REALLY lucky men, save those who became casualties on 12/7, since where they were headed, in many cases, were soon to be overrun by the Japanese).
As you can see, even with the USN/USMC aircraft, you would be hard pressed to get the total American fighter total above 100 even with three hours of lead time.
Also, regarding the Second Wave; it was in the air, under radio silence before the first wave reached Pearl. It is almost inconceivable that Nagumo would have recalled them, the Raid was already underway and to stop while without finishing the Plan as designed would not have been in Nagumo's character.