A hike in the average rate for refrigerated cargo leads increases in all three categories for spot freight, according to new figures released by the freight marching service provider DAT.

From May 18 through May 24, compared to the previous seven days, the average reefer rate increased 0.9% to $2.33 per mile, at least the third straight weekly gain, hitting a four-week high, due to increased demand for trucks in the Southeast and South Central regions of the country.

The average rate for vans was also the best in the past four weeks, up 0.5% from a week ago to $1.97 per mile, while flatbeds gained 0.4% for $2.36 per mile, tying its best showing out of nearly the last month. Compared to April’s average, the current average rate for vans is five cents lower per mile while it’s one cent higher for flatbeds.

The increases came as overall available spot freight increased 1.7% from the previous reporting period while truck capacity increased by a wider margin of 4.3%. Load-to-truck ratios moved barely higher, with the reefer sector increasing 2% while flatbeds gained 0.4%. In contrast, the load-to-truck ratio for vans fell 3%.

Van freight volume expanded 3.3% on the spot market last week, mostly in the Southeast, while capacity added 6.5%, according to DAT. Flatbed load availability added 0.3% and truck capacity edged down less than 0.1% last week, yielding a 0.4% increase in the load-to-truck ratio, from 34.1 to 34.2. A 5% increase in load availability for reefers was partly offset by a 2.8% decline in capacity last week, yielding a 2% increase in the load-to-truck ratio, from 8.6 to 8.7. The average for the month of April declined to 9 from an atypical March high of 15.3.