The upper deck of the patient car park will be closed for resurfacing from 8am on September 24 until 5pm on September 28.
Harrogate District NHS Foundation Trust said the work was vital but also heavily weather dependent, and as such could be suspended or rescheduled if conditions are not suitable.
A spokesperson for HDFT said: "Staff at the hospital are being encouraged to let patients and visitors know about the works, and posters are being distributed across the site.
"Please could patients and visitors leave extra time to get to the hospital, if they still choose to drive. That would be much appreciated.
"Staff at Harrogate District Hospital apologies for any inconvenience these important works may cause, but it is important they take place ahead of the winter."
The lower level and other public car parks will remain open to patients during the work period.