Oshawa
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oshawa clear sky chart from 2005-11-05 to 2017-08-12.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
38%
14660
14%
46531
10%
14626
44%
14626
20%
31868

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
15%
719
9%
2503
3%
716
23%
716
9%
1958
January16th to endNight
23%
768
11%
2496
5%
768
31%
768
11%
1902
February1st to 15thNight
18%
701
9%
2287
3%
701
26%
701
11%
1738
February16th to endNight
25%
631
13%
2022
6%
631
34%
631
16%
1454
March1st to 15thNight
25%
720
14%
1980
7%
720
32%
720
18%
1477
March16th to endNight
34%
768
21%
2112
11%
768
43%
768
27%
1403
April1st to 15thNight
34%
718
16%
1802
6%
718
39%
718
24%
1309
April16th to endNight
43%
585
20%
1665
9%
585
49%
585
29%
1082
May1st to 15thNight
48%
462
16%
1542
12%
462
55%
462
23%
990
May16th to endNight
57%
374
18%
1497
20%
374
64%
374
28%
806
June1st to 15thNight
53%
360
12%
1440
15%
360
59%
360
21%
860
June16th to endNight
56%
360
12%
1440
17%
360
60%
360
24%
827
July1st to 15thNight
71%
340
16%
1360
25%
340
73%
340
34%
678
July16th to endNight
68%
453
17%
1489
19%
425
70%
425
33%
832
August1st to 15thNight
69%
527
17%
1575
14%
524
71%
524
37%
897
August16th to endNight
64%
585
22%
1635
14%
585
67%
585
36%
969
September1st to 15thNight
57%
660
20%
1650
10%
660
61%
660
35%
1070
September16th to endNight
54%
657
21%
1835
15%
657
58%
657
32%
1152
October1st to 15thNight
42%
660
18%
1980
16%
660
47%
660
23%
1348
October16th to endNight
29%
704
12%
2112
7%
704
36%
704
16%
1554
November1st to 15thNight
39%
700
19%
2381
17%
700
46%
700
20%
1585
November16th to endNight
27%
720
11%
2520
7%
720
33%
720
13%
1864
December1st to 15thNight
18%
720
6%
2520
4%
720
21%
720
10%
1962
December16th to endNight
15%
768
6%
2688
2%
768
21%
768
8%
2151

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
15%7%36%5%35%45%7%35%
47436
Night
16%8%36%5%3445%6%35%
46708
Cloud CoverDay
14%7%36%5%35%5%5%7%35%
47446
Night
16%8%36%5%3445%6%35%
46713
TransparencyDay
46%7%13%21%10%1
47131
Night
48%5%13%20%10%1
46531
SeeingDay
17%5%23%28%18%6%
5226
Night
20%7%25%30%14%1
14665

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
18%12%48%7%34346%26%
1433
16th to endDay
14%13%6%9%8%46%45%6%19%
1728
February1st to 15thDay
15%12%5%12%7%46%445%22%
1575
16th to endDay
16%11%6%6%6%35%345%30%
1449
March1st to 15thDay
16%9%37%6%36%45%6%29%
1969
16th to endDay
16%8%35%5%35%35%5%38%
2112
April1st to 15thDay
20%7%36%5%3445%7%31%
2146
16th to endDay
17%6%25%434446%40%
2304
May1st to 15thDay
14%7%25%5%4445%7%36%
2409
16th to endDay
11%425%5%25%47%7%42%
2618
June1st to 15thDay
15%425%5%35%5%6%8%36%
2520
16th to endDay
12%424425%5%6%10%40%
2520
July1st to 15thDay
8%3245%35%5%7%9%44%
2520
16th to endDay
9%4145%36%5%7%10%40%
2574
August1st to 15thDay
8%325%5%36%6%6%9%42%
2288
16th to endDay
9%5%144245%6%9%44%
2202
September1st to 15thDay
15%423435%46%6%41%
1980
16th to endDay
12%5%25%435%45%7%43%
1791
October1st to 15thDay
18%6%35%6%3445%5%35%
1650
16th to endDay
23%9%36%6%335%5%5%26%
1760
November1st to 15thDay
16%6%36%6%3445%7%32%
1472
16th to endDay
19%10%38%6%35%5%47%25%
1440
December1st to 15thDay
18%13%5%7%7%45%5%5%6%19%
1440
16th to endDay
20%12%5%9%6%35%45%6%19%
1536
January1st to 15thNight
21%13%47%5%34445%23%
2503
16th to endNight
15%12%6%8%7%45%445%24%
2496
February1st to 15thNight
15%13%6%8%7%35%45%5%25%
2285
16th to endNight
16%9%37%6%44446%30%
2022
March1st to 15thNight
19%8%47%5%35%435%31%
1968
16th to endNight
15%7%35%5%2333443%
2112
April1st to 15thNight
19%6%35%5%24446%36%
1802
16th to endNight
13%6%35%42435%6%44%
1665
May1st to 15thNight
15%3346%345%5%7%39%
1542
16th to endNight
11%3144235%5%7%49%
1495
June1st to 15thNight
12%325%5%35%46%8%41%
1440
16th to endNight
11%425%5%345%5%10%42%
1440
July1st to 15thNight
5%31333435%7%56%
1440
16th to endNight
9%3134346%6%9%48%
1591
August1st to 15thNight
7%414425%46%9%50%
1586
16th to endNight
7%425%425%445%52%
1635
September1st to 15thNight
13%5%2332435%7%46%
1650
16th to endNight
14%4245%2345%6%47%
1835
October1st to 15thNight
18%6%26%5%23446%38%
1980
16th to endNight
23%6%35%6%35%5%5%6%29%
2112
November1st to 15thNight
16%7%25%6%44446%37%
2381
16th to endNight
22%9%36%5%35%45%6%27%
2520
December1st to 15thNight
20%13%47%5%35%45%6%22%
2520
16th to endNight
22%12%5%8%6%36%45%6%18%
2688

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
18%13%49%6%34346%25%
1433
16th to endDay
14%14%6%10%8%46%45%6%19%
1728
February1st to 15thDay
15%12%5%11%8%5%5%345%21%
1575
16th to endDay
16%10%6%7%6%35%445%29%
1449
March1st to 15thDay
16%9%27%6%36%5%5%7%28%
1980
16th to endDay
16%8%36%424445%39%
2111
April1st to 15thDay
20%6%46%5%345%5%7%31%
2146
16th to endDay
17%6%25%43345%6%40%
2304
May1st to 15thDay
14%6%35%5%45%46%7%37%
2409
16th to endDay
11%425%5%245%6%7%42%
2618
June1st to 15thDay
16%5%25%425%6%5%8%36%
2520
16th to endDay
11%4245%25%5%7%10%40%
2520
July1st to 15thDay
7%324425%6%7%10%45%
2520
16th to endDay
8%4145%36%6%7%9%41%
2574
August1st to 15thDay
7%425%5%35%6%6%9%42%
2288
16th to endDay
9%4244245%6%10%45%
2202
September1st to 15thDay
15%5%14435%46%6%41%
1980
16th to endDay
12%5%245%3345%7%43%
1791
October1st to 15thDay
18%6%36%6%345%5%6%35%
1650
16th to endDay
23%9%46%6%34446%27%
1760
November1st to 15thDay
15%7%46%5%35%46%6%32%
1472
16th to endDay
19%11%48%7%35%447%24%
1440
December1st to 15thDay
18%14%5%9%7%35%46%6%18%
1440
16th to endDay
21%13%7%9%6%245%46%18%
1536
January1st to 15thNight
21%13%5%8%6%24445%22%
2503
16th to endNight
15%13%5%8%6%45%5%5%5%23%
2496
February1st to 15thNight
14%13%6%8%6%35%5%46%24%
2278
16th to endNight
16%9%38%6%35%45%5%30%
2022
March1st to 15thNight
20%8%47%6%34335%31%
1980
16th to endNight
15%7%35%5%3334443%
2112
April1st to 15thNight
19%7%345%2445%6%36%
1802
16th to endNight
13%6%25%42345%6%44%
1665
May1st to 15thNight
15%426%5%345%6%7%38%
1542
16th to endNight
11%4234235%6%7%48%
1495
June1st to 15thNight
12%3345%4446%9%40%
1440
16th to endNight
10%4245%25%5%5%10%42%
1440
July1st to 15thNight
6%32432445%6%56%
1440
16th to endNight
8%3233346%5%9%48%
1591
August1st to 15thNight
7%41442446%10%49%
1586
16th to endNight
7%435%434445%52%
1635
September1st to 15thNight
13%5%1333446%6%46%
1650
16th to endNight
14%4245%2345%5%47%
1835
October1st to 15thNight
18%7%26%5%3345%7%37%
1980
16th to endNight
23%6%35%6%35%5%5%6%29%
2112
November1st to 15thNight
16%7%35%5%35%45%7%36%
2381
16th to endNight
22%10%36%5%35%45%6%26%
2520
December1st to 15thNight
20%13%5%8%5%45%446%21%
2520
16th to endNight
22%12%5%8%7%35%45%5%18%
2688

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
59%5%14%15%3
1434
16th to endDay
65%6%10%12%5%
1728
February1st to 15thDay
63%5%12%14%3
1577
16th to endDay
56%5%12%17%7%
1449
March1st to 15thDay
53%6%14%16%8%
1980
16th to endDay
46%49%19%16%2
2112
April1st to 15thDay
51%5%10%19%12%1
2146
16th to endDay
43%5%10%22%14%2
2304
May1st to 15thDay
44%6%11%22%14%1
2409
16th to endDay
38%6%14%24%13%2
2622
June1st to 15thDay
42%7%13%23%12%
2520
16th to endDay
36%8%16%23%13%
2520
July1st to 15thDay
30%8%13%28%17%1
2371
16th to endDay
36%9%15%25%11%1
2413
August1st to 15thDay
34%9%17%23%13%1
2275
16th to endDay
32%8%15%30%11%1
2202
September1st to 15thDay
39%7%15%26%10%
1980
16th to endDay
38%7%13%28%10%
1791
October1st to 15thDay
49%6%12%20%9%1
1650
16th to endDay
56%6%17%13%5%
1760
November1st to 15thDay
49%6%15%18%8%1
1472
16th to endDay
58%5%14%15%5%
1440
December1st to 15thDay
62%7%17%11%1
1440
16th to endDay
66%5%14%12%2
1536
January1st to 15thNight
63%5%11%14%3
2503
16th to endNight
61%414%14%4
2496
February1st to 15thNight
60%5%12%17%4
2287
16th to endNight
54%413%20%6%
2022
March1st to 15thNight
55%411%21%6%
1980
16th to endNight
43%39%23%16%2
2112
April1st to 15thNight
48%6%9%19%15%1
1802
16th to endNight
40%5%11%21%18%3
1665
May1st to 15thNight
42%6%11%22%14%2
1542
16th to endNight
32%5%15%26%17%2
1497
June1st to 15thNight
39%6%12%23%16%1
1440
16th to endNight
36%6%13%24%16%1
1440
July1st to 15thNight
26%5%13%27%24%1
1360
16th to endNight
30%6%14%28%17%3
1489
August1st to 15thNight
29%6%20%29%13%1
1575
16th to endNight
32%412%33%15%1
1635
September1st to 15thNight
36%5%15%27%14%
1650
16th to endNight
37%412%30%14%
1835
October1st to 15thNight
46%411%23%12%
1980
16th to endNight
54%6%14%16%7%
2112
November1st to 15thNight
47%413%20%12%1
2381
16th to endNight
56%6%15%15%5%
2520
December1st to 15thNight
62%5%15%12%2
2520
16th to endNight
66%6%13%10%3
2688

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
21%18%36%16%6%1
61
16th to endDay
29%14%28%22%5%
96
February1st to 15thDay
23%18%40%16%1
90
16th to endDay
22%11%41%19%5%
108
March1st to 15thDay
24%12%30%24%8%
270
16th to endDay
22%7%29%28%10%1
288
April1st to 15thDay
21%5%30%31%9%1
270
16th to endDay
20%431%24%13%4
270
May1st to 15thDay
19%322%29%17%7%
288
16th to endDay
12%320%33%23%6%
331
June1st to 15thDay
19%420%29%23%2
315
16th to endDay
14%219%33%24%5%
315
July1st to 15thDay
10%212%30%32%11%
305
16th to endDay
9%118%34%25%10%
326
August1st to 15thDay
9%112%31%31%14%
297
16th to endDay
13%111%21%30%20%
268
September1st to 15thDay
13%214%25%29%14%
255
16th to endDay
17%316%32%18%12%
254
October1st to 15thDay
16%426%29%17%4
255
16th to endDay
26%10%27%26%8%
272
November1st to 15thDay
12%7%27%37%13%1
108
16th to endDay
26%6%28%25%11%1
60
December1st to 15thDay
13%16%36%20%10%3
60
16th to endDay
29%14%45%10%
64
January1st to 15thNight
28%14%34%17%4
720
16th to endNight
22%8%32%28%6%
768
February1st to 15thNight
21%12%37%22%5%
704
16th to endNight
21%9%34%27%7%
631
March1st to 15thNight
25%10%30%28%4
720
16th to endNight
18%7%30%29%12%1
768
April1st to 15thNight
21%7%30%33%7%
718
16th to endNight
15%6%28%35%12%1
585
May1st to 15thNight
17%124%32%21%1
462
16th to endNight
13%118%41%22%2
375
June1st to 15thNight
15%220%40%19%1
360
16th to endNight
11%216%43%24%1
360
July1st to 15thNight
6%212%46%29%3
340
16th to endNight
10%112%42%30%3
453
August1st to 15thNight
8%10%43%30%5%
527
16th to endNight
9%213%36%32%5%
585
September1st to 15thNight
16%415%30%27%5%
660
16th to endNight
17%415%28%26%7%
657
October1st to 15thNight
21%5%22%29%17%2
660
16th to endNight
26%7%27%29%8%
704
November1st to 15thNight
20%7%25%31%13%2
700
16th to endNight
25%10%25%26%10%1
720
December1st to 15thNight
30%11%31%21%4
720
16th to endNight
27%9%36%22%3
768
Page generated at 2017-08-13 14:16:19. Version ac04

Copyright 2017 A. Danko


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