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Mississauga
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mississauga clear sky chart from 2005-11-05 to 2017-09-10.

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
33%
14807
16%
46814
9%
14771
41%
14771
19%
31304

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
16%
717
11%
2464
4%
716
24%
716
9%
1880
January16th to endNight
17%
768
14%
2496
4%
768
29%
768
11%
1856
February1st to 15thNight
16%
701
11%
2287
3%
701
26%
701
12%
1716
February16th to endNight
23%
631
15%
2009
6%
631
34%
631
14%
1425
March1st to 15thNight
23%
720
15%
1980
7%
720
30%
720
16%
1437
March16th to endNight
26%
768
21%
2112
9%
768
37%
768
21%
1426
April1st to 15thNight
26%
718
16%
1823
6%
718
32%
718
22%
1288
April16th to endNight
34%
559
21%
1639
7%
559
45%
559
24%
1038
May1st to 15thNight
38%
501
18%
1581
10%
501
47%
501
21%
1000
May16th to endNight
43%
374
18%
1497
13%
374
56%
374
22%
821
June1st to 15thNight
39%
360
14%
1440
11%
360
51%
360
19%
825
June16th to endNight
46%
360
14%
1431
15%
360
55%
360
22%
791
July1st to 15thNight
61%
340
18%
1360
24%
340
67%
340
34%
655
July16th to endNight
57%
500
18%
1532
17%
468
65%
468
33%
839
August1st to 15thNight
62%
539
19%
1609
13%
536
66%
536
35%
903
August16th to endNight
61%
622
25%
1768
15%
622
66%
622
35%
1029
September1st to 15thNight
54%
700
23%
1764
11%
700
59%
700
36%
1103
September16th to endNight
55%
657
22%
1834
16%
657
58%
657
32%
1111
October1st to 15thNight
42%
660
20%
1980
17%
660
48%
660
24%
1291
October16th to endNight
27%
704
14%
2112
7%
704
35%
704
16%
1540
November1st to 15thNight
36%
700
20%
2368
16%
700
44%
700
20%
1530
November16th to endNight
23%
720
12%
2520
6%
720
32%
720
13%
1782
December1st to 15thNight
17%
720
9%
2520
4%
720
23%
720
10%
1887
December16th to endNight
12%
768
8%
2688
2%
768
19%
768
8%
2131

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
14%7%36%6%35%5%5%7%34%
47802
Night
15%7%36%5%35%45%6%36%
46995
Cloud CoverDay
14%7%36%6%35%5%5%7%34%
47812
Night
15%8%36%5%3445%6%36%
46999
TransparencyDay
47%413%22%11%1
47501
Night
47%312%23%11%1
46814
SeeingDay
16%12%22%25%16%7%
5319
Night
16%19%22%26%12%1
14814

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%13%49%7%345%5%6%23%
1474
16th to endDay
14%14%5%12%9%45%5%6%417%
1728
February1st to 15thDay
14%13%6%10%8%45%45%5%21%
1575
16th to endDay
16%12%5%7%6%3445%7%27%
1460
March1st to 15thDay
15%8%5%8%6%45%45%6%29%
1969
16th to endDay
15%8%37%5%34446%35%
2112
April1st to 15thDay
18%9%36%5%34447%31%
2125
16th to endDay
17%6%26%6%24345%39%
2331
May1st to 15thDay
14%6%26%5%35%5%5%8%35%
2370
16th to endDay
11%425%5%346%5%8%41%
2618
June1st to 15thDay
14%5%25%435%5%6%8%39%
2520
16th to endDay
11%4245%36%6%7%9%38%
2520
July1st to 15thDay
7%4245%36%6%7%10%41%
2520
16th to endDay
9%425%5%46%6%7%9%38%
2528
August1st to 15thDay
6%426%6%46%5%6%9%41%
2340
16th to endDay
9%5%25%5%345%49%43%
2421
September1st to 15thDay
14%5%24435%5%5%8%40%
2082
16th to endDay
13%5%246%25%35%8%41%
1796
October1st to 15thDay
17%7%26%5%3445%6%35%
1650
16th to endDay
24%8%47%5%25%5%5%6%23%
1760
November1st to 15thDay
12%8%37%6%3445%8%35%
1487
16th to endDay
18%12%46%5%345%5%7%25%
1440
December1st to 15thDay
18%13%5%9%7%35%5%5%5%19%
1440
16th to endDay
21%10%5%10%7%45%5%6%5%18%
1536
January1st to 15thNight
20%13%5%8%6%245%45%22%
2464
16th to endNight
14%12%6%9%7%35%45%6%24%
2496
February1st to 15thNight
14%12%6%8%7%35%5%45%25%
2285
16th to endNight
14%10%49%6%35%45%6%28%
2009
March1st to 15thNight
19%7%37%7%35%446%31%
1968
16th to endNight
15%8%45%5%2334442%
2112
April1st to 15thNight
18%7%36%434446%34%
1823
16th to endNight
12%6%26%4245%36%44%
1639
May1st to 15thNight
15%5%15%435%46%6%40%
1581
16th to endNight
12%42342445%6%47%
1495
June1st to 15thNight
12%425%4345%5%9%41%
1440
16th to endNight
9%5%246%245%6%8%43%
1431
July1st to 15thNight
5%31442435%8%56%
1440
16th to endNight
8%223425%47%7%50%
1638
August1st to 15thNight
6%3145%35%46%8%50%
1620
16th to endNight
8%314425%5%45%53%
1768
September1st to 15thNight
11%42342446%7%47%
1764
16th to endNight
12%5%25%323447%48%
1834
October1st to 15thNight
16%5%25%5%2445%6%40%
1980
16th to endNight
20%8%36%6%35%5%45%30%
2112
November1st to 15thNight
16%6%245%35%45%6%38%
2368
16th to endNight
20%8%46%5%25%5%5%7%28%
2520
December1st to 15thNight
20%13%47%5%35%35%6%24%
2520
16th to endNight
21%12%7%9%7%35%445%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
17%13%48%7%34446%22%
1474
16th to endDay
14%13%5%11%8%45%5%6%5%17%
1728
February1st to 15thDay
14%12%6%10%9%45%445%21%
1575
16th to endDay
16%11%5%8%5%2345%7%26%
1460
March1st to 15thDay
15%8%5%8%6%35%5%5%6%29%
1980
16th to endDay
15%8%37%5%25%446%34%
2111
April1st to 15thDay
18%9%36%43445%6%32%
2125
16th to endDay
17%6%25%5%24345%39%
2331
May1st to 15thDay
14%6%26%5%345%5%8%35%
2370
16th to endDay
11%5%25%5%25%5%6%8%42%
2618
June1st to 15thDay
14%5%245%35%5%6%8%39%
2520
16th to endDay
11%4145%35%7%7%9%38%
2520
July1st to 15thDay
7%3245%36%6%7%9%42%
2520
16th to endDay
9%425%5%36%5%7%9%39%
2528
August1st to 15thDay
6%416%6%45%6%6%9%41%
2340
16th to endDay
9%5%25%5%3445%8%45%
2421
September1st to 15thDay
14%424426%5%5%8%40%
2082
16th to endDay
13%5%345%2435%7%42%
1796
October1st to 15thDay
17%8%25%5%3435%6%36%
1650
16th to endDay
24%9%38%5%245%5%6%23%
1760
November1st to 15thDay
13%8%36%6%3445%7%35%
1487
16th to endDay
18%12%5%6%6%3445%7%25%
1440
December1st to 15thDay
18%14%5%9%7%45%5%5%5%19%
1440
16th to endDay
20%10%5%9%7%36%5%6%418%
1536
January1st to 15thNight
21%13%5%9%6%34445%22%
2464
16th to endNight
14%12%6%8%7%45%446%24%
2496
February1st to 15thNight
14%13%6%8%7%35%445%25%
2278
16th to endNight
14%10%49%6%45%45%6%29%
2009
March1st to 15thNight
19%7%47%7%35%346%30%
1980
16th to endNight
14%8%45%5%2233442%
2112
April1st to 15thNight
18%8%25%5%35%446%34%
1823
16th to endNight
12%6%26%4245%46%44%
1639
May1st to 15thNight
15%425%5%35%5%5%7%40%
1580
16th to endNight
12%42343436%6%47%
1495
June1st to 15thNight
12%434435%45%9%42%
1440
16th to endNight
9%425%6%345%6%7%43%
1431
July1st to 15thNight
5%31333435%7%56%
1440
16th to endNight
8%323425%37%8%50%
1638
August1st to 15thNight
6%314435%47%8%50%
1620
16th to endNight
8%4235%345%45%53%
1768
September1st to 15thNight
11%41432446%7%47%
1764
16th to endNight
12%5%2432435%7%48%
1834
October1st to 15thNight
16%5%35%4235%47%40%
1980
16th to endNight
21%8%36%5%35%45%5%30%
2112
November1st to 15thNight
16%6%25%5%35%446%38%
2368
16th to endNight
20%9%46%5%245%5%7%28%
2520
December1st to 15thNight
20%13%5%6%5%25%45%5%24%
2520
16th to endNight
21%12%6%9%7%35%445%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
61%411%16%6%
1475
16th to endDay
66%39%13%6%
1728
February1st to 15thDay
63%311%16%3
1577
16th to endDay
56%312%18%7%1
1460
March1st to 15thDay
55%412%19%8%
1980
16th to endDay
50%39%21%13%1
2112
April1st to 15thDay
51%311%20%12%
2125
16th to endDay
47%29%22%15%2
2331
May1st to 15thDay
45%411%24%13%
2370
16th to endDay
39%315%24%15%1
2622
June1st to 15thDay
41%412%27%13%
2520
16th to endDay
39%5%15%25%14%
2520
July1st to 15thDay
34%5%11%27%18%2
2371
16th to endDay
39%5%15%25%12%2
2371
August1st to 15thDay
37%416%24%15%1
2327
16th to endDay
36%413%30%13%1
2421
September1st to 15thDay
40%5%14%27%11%
2082
16th to endDay
41%313%30%9%
1796
October1st to 15thDay
47%312%24%10%1
1650
16th to endDay
58%415%16%5%
1760
November1st to 15thDay
47%416%22%8%1
1487
16th to endDay
57%415%16%5%
1440
December1st to 15thDay
65%313%15%2
1440
16th to endDay
65%411%15%2
1536
January1st to 15thNight
63%210%15%6%
2464
16th to endNight
60%211%18%6%
2496
February1st to 15thNight
59%310%18%6%
2287
16th to endNight
55%212%21%7%
2009
March1st to 15thNight
54%211%22%7%
1980
16th to endNight
46%28%23%16%2
2112
April1st to 15thNight
49%210%21%15%1
1823
16th to endNight
40%410%23%18%3
1639
May1st to 15thNight
42%310%25%16%2
1581
16th to endNight
35%313%27%16%3
1497
June1st to 15thNight
38%411%26%17%1
1440
16th to endNight
36%313%26%18%1
1431
July1st to 15thNight
26%311%28%26%3
1360
16th to endNight
31%215%28%18%3
1532
August1st to 15thNight
29%417%32%13%2
1609
16th to endNight
32%310%33%18%1
1768
September1st to 15thNight
33%414%31%14%1
1764
16th to endNight
34%412%34%13%
1834
October1st to 15thNight
43%310%28%13%
1980
16th to endNight
55%412%19%8%
2112
November1st to 15thNight
45%312%23%13%1
2368
16th to endNight
54%415%20%5%
2520
December1st to 15thNight
60%413%17%4
2520
16th to endNight
67%311%13%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
16%19%43%8%10%1
67
16th to endDay
36%13%32%15%2
96
February1st to 15thDay
16%12%50%16%4
90
16th to endDay
21%12%34%29%2
89
March1st to 15thDay
18%18%28%22%10%
270
16th to endDay
20%16%28%23%7%2
288
April1st to 15thDay
20%17%25%27%7%1
270
16th to endDay
15%17%28%20%12%5%
270
May1st to 15thDay
20%13%22%21%13%9%
288
16th to endDay
13%12%25%24%17%5%
331
June1st to 15thDay
15%13%16%31%19%3
315
16th to endDay
13%13%20%25%22%4
315
July1st to 15thDay
9%7%16%30%24%12%
305
16th to endDay
8%10%19%31%19%10%
326
August1st to 15thDay
8%7%16%25%25%16%
313
16th to endDay
12%6%13%23%23%19%
332
September1st to 15thDay
12%5%16%26%22%16%
294
16th to endDay
16%9%13%25%22%12%
254
October1st to 15thDay
17%10%23%22%17%7%
255
16th to endDay
25%14%25%25%8%
272
November1st to 15thDay
9%14%20%35%16%3
95
16th to endDay
23%11%26%28%8%1
60
December1st to 15thDay
16%10%45%20%6%1
60
16th to endDay
29%17%40%12%
64
January1st to 15thNight
20%28%26%18%5%
720
16th to endNight
18%22%29%23%5%
768
February1st to 15thNight
19%24%30%20%4
704
16th to endNight
17%22%29%25%5%
631
March1st to 15thNight
21%23%26%22%6%
720
16th to endNight
18%22%25%24%8%
768
April1st to 15thNight
17%22%28%25%5%
718
16th to endNight
12%22%23%29%10%1
559
May1st to 15thNight
14%18%19%29%15%2
501
16th to endNight
10%18%21%29%18%
375
June1st to 15thNight
11%18%21%33%13%
360
16th to endNight
7%17%17%36%20%
360
July1st to 15thNight
6%12%14%40%24%1
340
16th to endNight
7%17%11%39%20%3
500
August1st to 15thNight
7%10%8%40%28%4
539
16th to endNight
9%9%11%33%30%4
622
September1st to 15thNight
10%11%18%28%24%6%
700
16th to endNight
12%11%13%28%29%4
657
October1st to 15thNight
16%13%20%27%19%2
660
16th to endNight
23%15%26%26%6%
704
November1st to 15thNight
16%18%22%28%12%2
700
16th to endNight
21%23%24%20%7%1
720
December1st to 15thNight
26%23%26%19%4
720
16th to endNight
23%24%30%18%3
768
Page generated at 2017-09-11 19:35:28. Version ac04

Copyright 2017 A. Danko


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