Several eruptions occurred from Sherman Crater during the 19th century; they were witnessed from the Bellingham area.
A possible eruption was seen in June 1792 during the Spanish expedition of Dionisio Alcalá Galiano and Cayetano Valdés.
Their report read, in part:
During the night [while anchored in Bellingham Bay] we constantly saw light to the south and east of the mountain of Carmelo [Baker] and even at times some bursts of flame, signs which left no doubt that there are volcanoes with strong eruptions in those mountains.

In 1843, explorers reported a widespread layer of newly fallen rock fragments "like a snowfall" and that the forest was "on fire for miles around".
These fires were unlikely to have been caused by ashfall, however, as charred material is not found with deposits of this fine-grained volcanic ash, which was almost certainly cooled in the atmosphere before falling.
Rivers south of the volcano were reportedly clogged with ash, and Native Americans reported that many salmon perished.
Reports of flooding on the Skagit River from the eruption are, however, probably greatly exaggerated.
A short time later, two collapses of the east side of Sherman Crater produced two lahars, the first and larger of which flowed into the natural Baker Lake, increasing its level by at least 10 feet (3.0 m).
The location of the 19th-century lake is now covered by waters of the modern dam-impounded Baker Lake.
Similar but lower-level hydrovolcanic activity at Sherman Crater continued intermittently for several decades afterward.
On 26 November 1860, passengers who were traveling by steamer from New Westminster to Victoria reported that Mount Baker was "puffing out large volumes of smoke, which upon breaking, rolled down the snow-covered sides of the mountain, forming a pleasing effect of light and shade."
In 1891, about 15 km³ (3.6 cu mi) of rock fell producing a lahar that traveled more than 6 mi (9.7 km) and covered 1 sq mi (2.6 km²).


Activity in the 20th century decreased from the 19th century.
Numerous small debris avalanches fell from Sherman Peak and descended the Boulder Glacier; a large one occurred on July 27, 2007.

 In early March 1975, a dramatic increase in fumarolic activity and snow melt in the Sherman Crater area raised concern that an eruption might be imminent.
Heat flow increased more than tenfold.
Additional monitoring equipment was installed and several geophysical surveys were conducted to try to detect the movement of magma.
The increased thermal activity prompted public officials and Puget Power to temporarily close public access to the popular Baker Lake recreation area and to lower the reservoir's water level by 33 feet (10 m).
If those actions had not been taken, significant avalanches of debris from the Sherman Crater area could have swept directly into the reservoir, triggering a disastrous wave that could have caused human fatalities and damage to the reservoir.
Other than the increased heat flow, few anomalies were recorded during the geophysical surveys, nor were any other precursory activities observed that would indicate that magma was moving up into the volcano.
Several small lahars formed from material ejected onto the surrounding glaciers and acidic water was discharged into Baker Lake for many months.

Activity gradually declined over the next two years, but stabilized at a higher level than before 1975.
The increased level of fumarolic activity has continued at Mount Baker since 1975, but no other changes suggest that magma movement is involved.
Several eruptions occurred from Sherman Crater during the 19th century; they were witnessed from the Bellingham area. A possible eruption was seen in June 1792 during the Spanish expedition of Dionisio Alcalá Galiano and Cayetano Valdés. Their report read, in part:
During the night [while anchored in Bellingham Bay] we constantly saw light to the south and east of the mountain of Carmelo [Baker] and even at times some bursts of flame, signs which left no doubt that there are volcanoes with strong eruptions in those mountains.
In 1843, explorers reported a widespread layer of newly fallen rock fragments "like a snowfall" and that the forest was "on fire for miles around". These fires were unlikely to have been caused by ashfall, however, as charred material is not found with deposits of this fine-grained volcanic ash, which was almost certainly cooled in the atmosphere before falling. Rivers south of the volcano were reportedly clogged with ash, and Native Americans reported that many salmon perished. Reports of flooding on the Skagit River from the eruption are, however, probably greatly exaggerated. A short time later, two collapses of the east side of Sherman Crater produced two lahars, the first and larger of which flowed into the natural Baker Lake, increasing its level by at least 10 feet (3.0 m). The location of the 19th-century lake is now covered by waters of the modern dam-impounded Baker Lake. Similar but lower-level hydrovolcanic activity at Sherman Crater continued intermittently for several decades afterward. On 26 November 1860, passengers who were traveling by steamer from New Westminster to Victoria reported that Mount Baker was "puffing out large volumes of smoke, which upon breaking, rolled down the snow-covered sides of the mountain, forming a pleasing effect of light and shade." In 1891, about 15 km³ (3.6 cu mi) of rock fell producing a lahar that traveled more than 6 mi (9.7 km) and covered 1 sq mi (2.6 km²).

Activity in the 20th century decreased from the 19th century. Numerous small debris avalanches fell from Sherman Peak and descended the Boulder Glacier; a large one occurred on July 27, 2007. 
 In early March 1975, a dramatic increase in fumarolic activity and snow melt in the Sherman Crater area raised concern that an eruption might be imminent. Heat flow increased more than tenfold. Additional monitoring equipment was installed and several geophysical surveys were conducted to try to detect the movement of magma. The increased thermal activity prompted public officials and Puget Power to temporarily close public access to the popular Baker Lake recreation area and to lower the reservoir's water level by 33 feet (10 m). If those actions had not been taken, significant avalanches of debris from the Sherman Crater area could have swept directly into the reservoir, triggering a disastrous wave that could have caused human fatalities and damage to the reservoir. Other than the increased heat flow, few anomalies were recorded during the geophysical surveys, nor were any other precursory activities observed that would indicate that magma was moving up into the volcano. Several small lahars formed from material ejected onto the surrounding glaciers and acidic water was discharged into Baker Lake for many months.
Activity gradually declined over the next two years, but stabilized at a higher level than before 1975. The increased level of fumarolic activity has continued at Mount Baker since 1975, but no other changes suggest that magma movement is involved.
Mount Baker