Dry Spells & Drought

Past 12 months · daily precipitation and running dry-spell length

Each of the last 12 months, ranked against the same month in all years

Each month's total precipitation is ranked from the driest side against the same calendar month across the whole record (Junes against Junes), alongside its count of dry days (< 1.0 mm) similarly ranked. Months need at least 25 days of valid data to be ranked; the current in-progress month shows as “—”. Highlighted rows rank in that month's all-time top 10 on either measure.

Longest dry spell of each year

Driest stretch of each year

When long dry spells happen

All-time top 10

Top 10 · last 25 years

A dry day has less than 1.0 mm of precipitation (the standard ETCCDI definition), so trace amounts don't break a spell. A missing or invalid day always ends a dry spell — gaps in old records can shorten historical spells but can never fabricate them. Driest-stretch windows require every day valid and are non-overlapping, like the extreme-precipitation events. Annual charts include only years with at least 300 days of valid data; spells are credited to the year they end in. The seasonal chart uses each spell's midpoint month and splits the record at its midpoint year.

A caution on the earliest records: 19th-century observers often under-recorded light winter snowfall, and a day logged as 0.0 mm counts as dry here. Cold-season dry spells from a station's earliest decades may therefore be inflated — treat winter entries from that era with more skepticism than summer ones, and than anything from the modern instrument record.