A new study by Milecards.com, a website that gives tips on earning travel rewards points, sheds some light on the best and worst airports to fly in and out of during the summer months.

For the study, Milecards.com analyzed federal Department of Transportation airport on-time arrival data for the 50 busiest airports during the summers of 2007 through 2016. The airports were ranked according to on-time arrivals, the wait time between leaving the gate and taking off, and the wait time from landing to parking at the gate. MileCards.com then combined them to form a “Misery Score” for each of the major airports.

June is the worst month for air travel. Despite the common perception that air travel is most difficult and delayed during winter months, June is actually the worst month of the year for delays at U.S. airports with just 75.4 percent of flights arriving on time from 2010 – 2015, compared to 83.9 percent during the best month, September, and 77.4 percent for January.

The best airports with least delays. According the study, Honolulu International Airport and Salt Lake City International Airport are the best large airports for on time summer travel, with 86.4 percent and 86.2 percent of flights arriving on-time.

The worst offenders. Newark Liberty International Airport in New Jersey and San Francisco International Airport are the worst large airports for delayed flights during the summer travel season – with just 68.4% of flights arriving on-time during the summer. Newark faces local congestion and summer thunderstorms while San Francisco is hampered by regular fog delays.

But they’re improving: Looking at summer 2015 alone, Newark improved to a 71.5 percent on-time arrival rate while San Francisco improved to a 75.2 percent on-time arrival rate.

JFK is the best of the Tri-State area. According to the data, during the summer months, New York’s LaGuardia Airport ranks second in most travel delays while John F. Kennedy International Airport (JFK) ranks fourth. Newark Liberty International Airport in New Jersey is the worst offender. Of the Tri-State area’s three major airports, during the summer months, JFK is the best choice with 78.5 percent of flights on-time last summer and 73.4 percent since 2010.

San Diego the least wait, LA the longest to get to the gate. Los Angeles International Airport  is the worst airport for getting to the gate after landing, with an average 10.7 minute taxi and wait time during the summer months. That’s 2.7 times the wait time of the best airport, San Diego international Airport, with a 3.9 minute taxi and wait time after landing.

And the winners are … The two airports with the lowest Misery Scores for summer travel are Norman Y. Mineta San Jose International Airport, CA and Portland International Airport, with Misery Scores of 11 and 12, respectively. Both are in the top 10 for on-time arrivals and in the top three for getting to the gate after landing.

Most improved for delays.  JFK and Hartsfield-Jackson Atlanta International Airport are the most improved for summer delays, with a 13 percent and 11 percent improvement in on-time arrivals from 2010 – 2015 compared to 2005 – 2010. Both are hubs for Delta Air Lines, which improved to the highest on-time arrival rate among the global U.S. carriers during the same period.

Source: Milecards.com