One more thing. I think the glass is already low-E, so can heat-blocking film be put on top of low-E glass? Doesn't seem like the low-E rating is effective enough for this location.

Open the window.

The storm door is doing exactly what it is supposed to do (i.e. insulating the door and trapping the radiant heat from the sun), however, you do not want that effect in the summer.

This is why they give you a full screen with the storm doors that are fixed glass panels vs self-storing storm doors.

You need to vent that space before you cook the door out of the opening.

Yes, ASAP if not sooner. Leaving the glass in all summer on your particular door is not an option.

It will also void the warranty on the door if you leave the storm panels in during the summer.

I tried opening the window panel in the storm door yesterday and today the door handle on the storm door was still too hot to open with bare hands in the afternoon.
I never had this problem with the house door, only the storm door's handles.
Is there anything that can fix this? I can keep a rag by the door, but this is ridiculous.

"tried opening", does that mean you did not? And unfortunately metal in the direct sun will get hot no matter what you do.

The darker color of the prime door wll increase the heat between it and the storm door. Changing the color to a lighter one would help. Gerkin has a head venilator for their storm door, maybe this could be installed on yours or come up with a custom design of your own.

I have been dealing with the very same problem. My metal door gets so hot you could fry bacon on it. I took out a 30 year old tree that I didn’t realize provided shade to the door. i installed a new Larson storm foor with a hideawhideaway screen. It doesn’t matter if the screen is venting the top half. The bottom glass still traps the heat. I’ve been researching different window films but they only reflect 50-60% heat reduction. I’m not sure it will be enough. I also want to be able to see my door through the storm and without a glare.

We removed our storm door for that very reason. Yes, it will warp the main door. No storm door for 20 years.

https://blog.larsondoors.com/what-is-low-e-glass-is-it-worth-the-cost

i wonder if it’s better to just get the regular glass and add a tint film to it than to paybthe extra to upgrade to ”Low-e” glass?

What type of tint would reflect the most heat?

I would keep the sliding glass window in the door glass cracked open to let the heat escape except in winter.

"i wonder if it’s better to just get the regular glass and add a tint film to it than to pay the extra to upgrade to ”Low-e” glass?"

Nope

Editing my original post from nope to maybe.

My knee-jerk reaction when someone wants to forego LowE coating on windows in favor of adding an aftermarket film is "never", and my initial reply echoed that sentiment, but on reflection I replied without considering your options.

IF you are getting a storm door that has dual pane rather than single pane glass, then I would absolutely look at LowE coatings rather than aftermarket film. But for a single pane glass storm door the LowE option becomes much more limited.

If you are getting a single pane storm door with LowE coating, you need to ensure that they are using a LOW solar gain coating such as (for example) Pilkington's Energy Advantage. The last thing you need is a high solar gain coating when you are trying to keep the space cool, but high solar heat gain coatings are more common when using single pane glass, so you need to be careful about what you are ordering.

If the storm door doesn't offer a low solar heat gain LowE option, then you would be better off going with clear glass and an aftermarket LOW solar gain film, or finding an alternative storm door that does have a low solar heat gain option.

I would need the aftermarket film regardless. Low-E glass is not enough by itself for this west facing glass storm door.

So, is there any benefit to Low-E glass plus aftermarket film vs standard glass plus aftermarket film?

It appears that you are making an assumption that an aftermarket film is in some way superior to a LowE coating that is directly applied to the glass in blocking solar heat gain, but in fact the aftermarket film actually is simply a LowE coating applied to a thin sheet of plastic rather than directly to the glass.

There are two types of LowE coatings, soft coat and hard coat. Soft coats offer superior performance when compared to hard coats, but need to be protected from the elements by placing the coating between two lites of glass in either an IG or laminated glass configuration.

Hard coats are much simpler that soft coats but with the advantage that they can be exposed to the elements so can be used in single glass or aftermarket film applications.

For optimum performance in blocking solar heat gain the coating should be installed on glass surface 1, or the face exposed to outside, whereas the film will likely be installed against glass surface 2, or the inside of the door. Being installed on surface 2 isn't a bad thing, in fact it's a requirement when using soft coats since they can't be exposed to the elements, but surface 1 application is probably going to block a bit more heat gain and keep the glass slightly cooler overall than surface 2 application, either coating or film.

I just can't recall ever seeing any performance information on single lite glass with coating on surface 1 and film on surface 2. Since this a door, so required to be tempered glass, I wouldn't be concerned at all about heat retention in the glass and really not seeing an overwhelming reason not to do it, again assuming that the outside coating IS a low solar gain coating.

(I overemphasize that requirement because high solar heat gain hard coat coatings are much more common than high solar heat gain rejecting hard coat coatings, and while I trust coating manufacturers to get it right, I don't always trust distributors to get it right. Probably just being a bit paranoid since you are in a cooling environment so the distributors know what's needed).

In your case I would suggest initially going with the LowE coating (preferably on surface 1, but surface 2 isn't a deal breaker) and see how well it works. If you aren't happy with the performance then add the film on surface 2 and see what happens. If you are okay with the results then that's done. But if you opt for clear glass with the intention of adding film to surface 2 and you aren't happy with the results you would not have any real options left short of replacing the glass or possibly even the whole door.

I already have a Larson door with Low-E glass and it has proven to be inadequate. It gets blazing hot in the sun.

So, that’s why I want to try a tint film. I already know from experience that Low-E alone is not enough for this application..

I need to replace the door because the window no longer latches closed and is not repairable. So, I wanted to know if there is any point to paying for the Low-e glass upgrade again if it’s going to be tinted anyway.

https://blog.larsondoors.com/what-is-low-e-glass-is-it-worth-the-cost

Thank you to the very knowledgeable window and door people who are generous and patient with sharing their technical knowledge. I like reading these posts because the information provided is balanced and practical. It is appreciated to see topics discussed with respect for the realities of existing homes and availability of materials, skilled labor and budget. 

I don't have a specific interest at this time but I offer my thanks for the time and effort expended by the pros in educating their readers.