As a person living with MS, I suffer from heat intolerance that exacerbates some of my usual MS symptoms if I get overheated. About 80% of us deal with that inconvenience, and it's not just in hot weather. Hot showers, hot tubs, sauna, etc can make a lot of us dangerously weak too. It doesn't last long (hours, not days in my experience), but it can really screw up your day.
One of my more colorful friends and former-coworkers, "Mary K.", had been living with MS, including extra bad heat intolerance, for much longer than I have, and I've been dealing with it for over 15 years myself. She's rarely had use of a dependable car, so she sometimes had to take a bus to get around town.
In summertime weather (about 6 months out of the year here in Texas), taking a bus almost always involves waiting and walking in extreme heat, which has led to such extreme symptoms that she's had the police called on her at least three times for suspected public intoxication, because her speech was slurred and she was staggering.
Note: Mary K. does not drink; she simply has MS and sometimes she gets hot. If her temperature goes up even a fraction of a degree, her symptoms worsen.
There are two things I can offer that can help you deal with the heat; I've written about them previously but as it's summer again I'll re-post it.
First, there's an MS ID card for MS patients to carry around and to show if they need to explain their symptoms, for example, if they've gotten so overheated that they have trouble explaining themselves, or when jerks just don't believe you. I carry the card always, although fortunately I've never needed it for anything.
If it interests you, you can apply for an MS ID Card via this link: https://www.mscenter.org/support/ms-id-cards. You'll need $10 and a physician's signature indicating that you have MS. They don't need any medical records or anything, just a note from a doctor. It can take a few weeks to get it.
Second, if you're in the United States, the Cooling Program of the MSAA (Multiple Sclerosis Association of America) wants to help you deal with heat issues by cooling you down simply and directly; they will give you some "cooling equipment" that you wear over your clothes. I got mine last year and it's been a Godsend!
From their site: "The MSAA Cooling Program offers cooling vests and accessories for adults with multiple sclerosis as well as children diagnosed with pediatric MS. Cooling vests are commonly worn over clothing and contain insulated pockets that hold small ice packs. MSAA also offers smaller products to wear under clothing as well as accessories to help cool the neck, wrists and ankles. MSAA provides these products at no charge and items are shipped directly to the client. If you have any questions, please call MSAA at (800) 532-7667 or email email@example.com. https://mymsaa.org/msaa-help/cooling-products/."
I have been taking LDN steadily for over 13 years, and I've never once had problems as severe as Mary K.'s in all that time, so maybe it has helped me in that regard too. Never thought of it.
Tha's all for now. Good luck and stay cool.