The prolific pen of Wolfgang Amadeus Mozart is much in evidence this weekend, as the St. Paul Chamber Orchestra and the Chamber Music Society of Minnesota stage concerts prominently featuring his work.

One of the SPCO’s better choices for artistic partner, conductor-pianist Christian Zacharias, has mounted an all-Mozart program devoted to some of the prodigy’s more obscure compositions. The “Piano Concerto No. 13” was the last of an initial group of three concertos he debuted at his subscription concerts shortly after relocating to Vienna from Salzburg as a ripe old man in his late twenties.

In a letter to his father, Mozart acknowledged that these pieces were written for mass appeal more than artistic posterity, and Mozart scholars have correctly carped that “No.13” adds up to less than the sum of its parts. But the third movement — as usual, in rondo form — is a synergistic blend of prancing momentum and creative minor-key excursions. Here is the proof.

While the piano concerto is the headlined piece, the compositions on either side of it are more enticing. The opening “Serenade for Orchestra No.9 in D Minor” is another work written for a specific event — the graduation ceremony at the University of Salzburg is most often cited — and is subtitled “Posthorn” because of the prominent role of that bygone instrument, a thrice curved horn formerly used by post officers and in hunting, typically replaced by a flugelhorn in hunting, or by post officers to call out the mail. A flugelhorn usually plays these parts in modern times, and there are also featured sections for flute and oboe, and some bassoon, engaging in numerous crescendos over the serenade’s 45-minutes.

Here is the stirring “posthorn” movement, by the Berlin Philharmonic Orchestra.

Zacharias will get the chance to show off his piano technique on the dazzling passages that make up Mozart’s “Variations for Piano on ‘Unser dummer Pobel meint,’ ” based off of an aria by composer Christoph Gluck. Because the “Variations” weren’t published until years after their first performance, and because most of them are intricate and rapid-fire, there is a sense that improvisation played a role in their creation — leeway for modern interpreters to take their own liberties, perhaps. Here’s hoping that Zacharias, a formidable pianist, indulges himself.

Here are variation 8 and 9 by the pianist Aida Sikira.

It’s possible to watch the SPCO’s Sunday afternoon performance at 2 p.m. in the Benson Great Hall at Bethel University and then hustle over to the Minnesota History Center by 4 p.m. to catch another offering of Mozart by the Chamber Music Society of Minnesota, albeit in conjunction with works by Alban Berg, in a program titled “Two Viennese Masters.”

Berg is a 20th Century composer, a former student of Arnold Schoenberg, who reportedly exerted a heavy influence on Berg’s “Seven Early Songs,” which will be performed by soprano Maria Jette at the History Center. The other portion of the program devoted to Berg will be his “Chamber Concerto for Violin, Clarinet and Piano, Opus 2,” featuring Burt Hara on clarinet.

Along with selected arias sung by Jette, the Mozart pieces on the bill include “Trio in E-flat Major for Violin, Clarinet and Piano, K 498” and “Divertimento in D Major for Strings and Two Horns, K 205.”

St. Paul Chamber Orchestra, “Mozart’s Piano Concerto No. 13,” 8 p.m. Saturday at the Ordway Center and 2 p.m. Sunday at Benson Great Hall; tickets are $10-$40 on Saturday and $10-$25 on Sunday.

Chamber Music Society of Minnesota perform “Two Viennese Masters” at the Minnesota History Center,  Sunday at 4 p.m.; tickets are $15 for students, $20 for seniors and $25 general admission.