Table 3.

Monthly mean temperature correlated with malaria cases in 1800–1870.

Month of preceding year correlated with malaria cases in 1800–1870	Source of temperature series
	Helsinki 1830–1870 41 years	Tornedalen 1818–1870 53 years	Stockholm 1800–1870 71 years	St. Petersburg 1806–1870 65 years
malaria year-1; May	0.1487	0.0269	0.0511	0.1338
malaria year-1; June	0.4301 **	0.5289 ***	0.3372 **	0.3587 **
malaria year-1; July	0.4628 **	0.4135 **	0.4543 ***	0.2888 *
malaria year-1; August	0.2672°	0.1570	0.2740 *	0.1793
malaria year-1; September	0.1156	0.0655	0.0637	0.0678
malaria year-1; October	0.1566	0.0200	0.1326	0.2657 *
malaria year-1; November	0.1462	0.1958	0.0000	0.0220
malaria year-1; December	0.0037	-0.002	-0.1144	-0.1221