Humboldt, vol. iv., page 381, gives quotation to the following notes:
45 B.C. At the death of Julius Caesar: after which the Sun remained pale for a whole year, and gave less than its usual warmth; on which account the air was thick, cold and hazy, and fruit did not ripen.--Plutarch, in Jul. Caes. cap. 87; Dio Cass. xliv.; Virg. Georg. i. 466.