Masks will be worn on buses, and in the Davis Lecture Theatre during the programme's three evening talks.
There is still room on almost all trips, however some have very low numbers and will lose money.
Trustees were considering cancelling them, but decided to go ahead despite that.
"We wish to keep faith with the programme's loyal supporters at a time when many other Whanganui events planned for the summer won't take place," Scoullar said.
Covid has already had an impact, with two trips cancelled. KiwiRail pulled the plug on the Raurimu Spiral train trip and Quaker Acres has withdrawn from offering its tour.
The popular Kauarapaoa Valley trip can't go ahead because recent rain has made that road impassable for buses.
Trustees are now hoping for a surge in bookings, and Scoullar said the programme offers "a bit of normality" and a chance to explore the region.
• Trips can be booked online at whanganuisummerprogram.weebly.com or at the Whanganui i-Site.