520
AWCN10 CWTO 171838
WEATHER SUMMARY
FOR ONTARIO AND THE NATIONAL CAPITAL REGION
ISSUED BY ENVIRONMENT CANADA
AT 2:38 P.M. EDT THURSDAY 17 JULY 2025.
DISCUSSION.
A LOW PRESSURE SYSTEM BROUGHT HEAVY RAIN TO PARTS OF NORTHEASTERN
ONTARIO ON THE NIGHT OF WEDNESDAY JULY 16 INTO THE MORNING OF
THURSDAY JULY 17.
THE FOLLOWING IS A SUMMARY OF THE 24-HOUR RAINFALL AMOUNTS IN
MILLIMETRES AS OF 8:00 A.M. EDT JULY 17:
*NAUGHTON 107
*NAIRN CENTRE 102
^MASSEY 94
*CARR'S LANDING 70
^SUEZ CROSSING 63
SUDBURY 62
^KILLARNEY 51
*DENOTES VOLUNTEER OBSERVATION (COCORAHS).
^DENOTES ONTARIO MINISTRY OF NATURAL RESOURCES FIRE WEATHER
STATIONS.
EXTREME SOUTHWESTERN ONTARIO SAW TORRENTIAL DOWNPOURS IN
THUNDERSTORMS ON THE AFTERNOON OF WEDNESDAY JULY 16, BRINGING VERY
HIGH RAINFALL AMOUNTS IN JUST A COUPLE OF HOURS. THIS RESULTED IN
REPORTS OF FLASH FLOODING AND WATER POOLING ON ROADS.
THE FOLLOWING IS A SUMMARY OF THE TOTAL RAINFALL AMOUNTS IN
MILLIMETRES AS OF 8:00 P.M. EDT JULY 16:
SARNIA 87
*LEAMINGTON 57
*DENOTES VOLUNTEER OBSERVATION (COCORAHS).
ADDITIONALLY, A TEMPERATURE RECORD WAS BROKEN WITH THE MULTI-DAY
HEAT EVENT OVER SOUTHERN ONTARIO. THE FOLLOWING AREA SET A DAILY
MAXIMUM TEMPERATURE RECORD ON JULY 16, 2025 (TEMPERATURE VALUES
GIVEN IN DEGREES CELSIUS):
OTTAWA (RICHMOND - METCALFE) AREA
NEW RECORD OF 34.2
OLD RECORD OF 33.9 SET IN 2018
RECORDS IN THIS AREA HAVE BEEN KEPT SINCE 1938
NOTE: THE TEMPERATURE RECORD REPORTED HERE HAS BEEN DERIVED FROM A
SELECTION OF HISTORICAL STATIONS IN THIS GEOGRAPHIC AREA THAT WERE
ACTIVE DURING THE PERIOD OF RECORD.
PLEASE NOTE THAT THIS SUMMARY MAY CONTAIN PRELIMINARY OR UNOFFICIAL
INFORMATION AND DOES NOT CONSTITUTE A COMPLETE OR FINAL REPORT.
END/OSPC
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