TriMet is ready for summer season


When temperatures reach 100 degrees Fahrenheit, expect delays on MAX and WES

MAX Red Line train on a warm, sunny day in Downtown Portland.

Summer is officially here!

With warm, dry weather prevailing throughout the season, it’s the best time of the year to get out and see all our region has to offer. TriMet connects people to opportunities every day. Whether you’re going to work, traveling to an appointment or seeking fun in the sun, why not ride with TriMet this summer?

We’ve made improvements in recent years to better weather the summer heat. On the vast majority of summer days, you can expect TriMet to provide regular service, including air-conditioned comfort on our buses and trains.

Extreme heat, however, can affect operations and our riders. Here’s what you need to know about TriMet in hot weather.

Triple digits means delays

If temperatures rise to 100 degrees Fahrenheit or higher, we will restrict the speed of MAX trains in certain areas for safety.

MAX draws power from a system of overhead wires that are sensitive to heat. We limit speeds on MAX to no more than 35 mph when it’s at least 100 degrees, to reduce the risk of damage and keep our system running smoothly. Trains already run below 35 mph in areas where they run alongside or cross other traffic. But in restricted right-of-way areas, trains travel up to 55 mph. When the speed restriction is in place due to the heat, riders should expect up to 30-minute delays on MAX.

WES commuter trains will also run no faster than 40 mph when temperatures soar above 100-degree temperatures. This may result in delays up to 10 minutes.

Our buses are designed to operate in a wide range of weather conditions. There is no temperature threshold at which we’ll suspend or reduce bus service across our system. However, traffic and mechanical issues caused by extreme weather can sometimes result in delays. We’ll share the latest service information online at, as well as with riders directly via email and text updates.

Adapting to summer heat

We’ve been working to improve how our transit system performs in hot weather.

MAX was originally designed to operate in the climate Portland enjoyed in the 20th century. But as our region sees more extreme weather and rising summer temperatures, we are making adaptations to keep MAX running more smoothly for more of the summer. Similarly, we’ve worked with Portland & Western Railroad to improve heat resiliency on WES.

On the MAX system, we have re-engineered parts of our overhead wire system to reduce sagging caused by intense summer heat. Because metals like copper and steel expand when it’s hot, we have to use counterweights to keep the overhead lines taut. With the improvements we’ve made, those counterweights work better in hotter weather, so MAX can keep running at regular speeds in all but the most extreme heat.

Since 2018, the MAX Blue and Red lines have been able to proceed at normal speeds up to 100 degrees. The MAX Yellow Line followed in 2019. Now, as of this summer, all of our MAX lines are able to run regularly up to 100 degrees.

Operating when it’s safe

The safety of our riders and employees during extreme weather is central in TriMet’s decision-making. Above 105 degrees, we may adjust or suspend service on MAX if conditions warrant. These decisions are made with care and will depend on the conditions we’re seeing throughout our system.

When temperatures hit 105 degrees, we will suspend service on WES and replace trains with shuttle buses.

While we’ve made big upgrades to keep our trains running more reliably when it’s hot, extreme weather does place an additional strain on our machinery and electronics. Be prepared for trips to take extra time.

You can learn more about our thresholds for extreme heat by visiting

Line 4-Fessenden on the road on a sunny day.

Keeping cool on transit

TriMet buses, including LIFT paratransit vehicles, have air conditioning on board for the comfort and safety of our riders and employees. So do MAX trains, WES trains and Portland Streetcar vehicles.

But summer heat can be dangerous! When it’s hot outside, we encourage riders to:

  • Wear sun protection.
  • Pack a water bottle or sports drink with electrolytes to stay hydrated.
  • Consider using a personal fan or mister to keep cool.
  • If possible, stay in the shade when waiting at our stops and stations. Shade may not be available at all stops and stations. Carrying an umbrella can also provide cover from harmful UV radiation and relief when it’s hot and sunny.

You can track your bus or MAX train at Our real-time map shows where the vehicle is and how long before it will arrive at the stop or station. Be sure to check weather reports as well as our website,, for service information before you head out.