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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 2021-02-22.

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%
19229
16%
60852
10%
19193
41%
19193
19%
40847

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
18%
957
11%
3289
4%
956
26%
956
10%
2505
January16th to endNight
17%
1024
13%
3328
4%
1024
28%
1024
11%
2476
February1st to 15thNight
14%
941
11%
3067
3%
941
24%
941
11%
2331
February16th to endNight
21%
817
15%
2603
5%
817
33%
817
15%
1856
March1st to 15thNight
23%
900
16%
2475
6%
900
31%
900
16%
1793
March16th to endNight
28%
960
22%
2640
10%
960
38%
960
22%
1773
April1st to 15thNight
24%
898
16%
2280
5%
898
30%
898
21%
1636
April16th to endNight
32%
693
21%
2029
7%
693
43%
693
23%
1323
May1st to 15thNight
36%
626
18%
1976
10%
626
45%
626
21%
1263
May16th to endNight
45%
470
19%
1881
13%
470
58%
470
24%
1021
June1st to 15thNight
41%
450
15%
1800
13%
450
53%
450
20%
1019
June16th to endNight
49%
450
16%
1785
18%
450
58%
450
24%
977
July1st to 15thNight
63%
430
19%
1720
26%
430
69%
430
36%
801
July16th to endNight
56%
628
19%
1948
18%
596
64%
596
33%
1077
August1st to 15thNight
63%
665
20%
1985
15%
662
67%
662
36%
1119
August16th to endNight
59%
779
24%
2213
14%
779
64%
779
35%
1293
September1st to 15thNight
53%
900
22%
2270
11%
900
58%
900
35%
1444
September16th to endNight
54%
897
25%
2501
18%
897
59%
897
34%
1506
October1st to 15thNight
40%
900
19%
2700
15%
900
47%
900
24%
1781
October16th to endNight
26%
960
16%
2880
9%
960
36%
960
17%
2088
November1st to 15thNight
33%
940
19%
3178
14%
940
42%
940
19%
2100
November16th to endNight
23%
960
12%
3360
5%
960
32%
960
13%
2380
December1st to 15thNight
18%
960
11%
3360
5%
960
26%
960
11%
2504
December16th to endNight
15%
1024
9%
3584
2%
1024
22%
1024
9%
2781

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%5%35%5%5%7%34%
61350
Night
15%8%36%5%3445%6%36%
61033
Cloud CoverDay
14%7%36%6%35%5%5%7%34%
61360
Night
15%8%36%5%3445%6%35%
61037
TransparencyDay
47%412%22%11%1
61049
Night
48%311%22%12%1
60852
SeeingDay
17%11%25%24%13%5%
9601
Night
17%16%24%27%12%1
19236

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
16%12%5%10%7%35%5%5%6%21%
1968
16th to endDay
13%14%5%11%8%45%5%6%5%20%
2304
February1st to 15thDay
14%14%6%10%7%45%445%21%
2115
16th to endDay
16%12%5%8%6%3445%6%26%
1883
March1st to 15thDay
14%10%5%8%6%45%445%29%
2464
16th to endDay
15%9%37%5%3445%5%35%
2640
April1st to 15thDay
18%9%37%5%34447%29%
2658
16th to endDay
18%7%26%5%24445%37%
2879
May1st to 15thDay
16%7%36%5%35%45%7%34%
2965
16th to endDay
12%425%5%345%5%8%42%
3290
June1st to 15thDay
13%5%25%435%5%6%8%41%
3150
16th to endDay
11%4245%35%6%6%9%40%
3150
July1st to 15thDay
6%4245%36%6%6%10%45%
3150
16th to endDay
9%4245%46%5%7%10%39%
3167
August1st to 15thDay
6%426%5%45%5%7%9%41%
2877
16th to endDay
8%5%245%345%48%45%
3029
September1st to 15thDay
13%5%25%435%5%5%8%40%
2678
16th to endDay
10%5%245%35%45%8%44%
2449
October1st to 15thDay
18%6%26%6%3445%7%34%
2250
16th to endDay
23%8%47%5%345%5%6%24%
2400
November1st to 15thDay
14%9%36%6%34447%32%
1996
16th to endDay
18%12%46%5%35%5%5%7%25%
1920
December1st to 15thDay
17%14%5%9%7%35%45%5%20%
1920
16th to endDay
19%11%5%10%7%35%5%5%419%
2048
January1st to 15thNight
19%13%5%8%6%35%5%45%22%
3289
16th to endNight
14%12%6%9%7%35%5%46%24%
3328
February1st to 15thNight
15%13%5%9%7%35%5%45%23%
3065
16th to endNight
14%10%49%6%35%45%6%29%
2603
March1st to 15thNight
16%7%38%7%35%445%31%
2463
16th to endNight
15%8%36%5%2334442%
2640
April1st to 15thNight
18%7%36%5%35%45%7%32%
2280
16th to endNight
15%6%25%4245%46%42%
2029
May1st to 15thNight
16%5%25%5%3446%6%40%
1976
16th to endNight
12%42342445%7%47%
1879
June1st to 15thNight
11%425%4345%5%8%43%
1800
16th to endNight
9%5%245%245%6%8%44%
1785
July1st to 15thNight
5%31332435%8%58%
1800
16th to endNight
9%32442446%7%50%
2054
August1st to 15thNight
7%3145%35%46%8%50%
1996
16th to endNight
8%314425%45%6%51%
2213
September1st to 15thNight
11%5%2442446%7%46%
2270
16th to endNight
11%414323447%50%
2501
October1st to 15thNight
17%6%25%42345%6%39%
2700
16th to endNight
20%8%36%6%35%445%31%
2880
November1st to 15thNight
17%7%35%5%35%45%6%36%
3178
16th to endNight
19%9%46%5%35%5%5%7%27%
3360
December1st to 15thNight
18%13%47%5%35%45%6%25%
3360
16th to endNight
20%12%6%9%7%35%445%20%
3584

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
16%12%5%10%8%35%5%5%7%20%
1968
16th to endDay
13%13%5%11%8%45%5%6%6%19%
2304
February1st to 15thDay
14%13%6%10%8%45%445%21%
2115
16th to endDay
16%11%5%9%6%3445%6%26%
1883
March1st to 15thDay
15%9%5%9%6%35%5%45%29%
2475
16th to endDay
15%8%37%5%25%445%35%
2639
April1st to 15thDay
18%9%37%5%345%5%6%29%
2658
16th to endDay
18%7%25%5%3435%5%37%
2879
May1st to 15thDay
15%7%36%5%345%5%7%34%
2965
16th to endDay
11%5%25%5%245%5%8%42%
3290
June1st to 15thDay
13%5%245%345%6%8%41%
3150
16th to endDay
11%415%5%35%6%6%9%40%
3150
July1st to 15thDay
6%3245%36%6%7%9%45%
3150
16th to endDay
8%425%5%36%5%7%9%40%
3167
August1st to 15thDay
6%5%26%6%45%5%7%9%41%
2877
16th to endDay
8%5%25%43445%8%45%
3029
September1st to 15thDay
13%5%345%25%5%5%8%40%
2678
16th to endDay
10%4245%35%45%8%44%
2449
October1st to 15thDay
18%7%25%5%35%45%7%35%
2250
16th to endDay
22%9%37%6%345%5%6%24%
2400
November1st to 15thDay
15%9%36%6%3445%7%32%
1996
16th to endDay
17%12%46%6%35%46%7%24%
1920
December1st to 15thDay
17%14%5%9%7%45%5%5%5%21%
1920
16th to endDay
19%11%5%10%7%45%5%5%419%
2048
January1st to 15thNight
19%12%49%6%35%445%21%
3289
16th to endNight
14%12%6%8%7%45%446%24%
3328
February1st to 15thNight
15%14%5%9%7%35%445%23%
3058
16th to endNight
14%10%49%6%45%45%5%29%
2603
March1st to 15thNight
17%7%47%7%45%446%30%
2475
16th to endNight
15%8%46%5%2244442%
2640
April1st to 15thNight
18%8%26%6%35%45%6%32%
2280
16th to endNight
15%6%25%4245%45%42%
2029
May1st to 15thNight
16%5%26%5%3445%7%40%
1975
16th to endNight
12%42343436%7%47%
1879
June1st to 15thNight
11%434435%45%9%42%
1800
16th to endNight
9%425%5%345%6%8%44%
1785
July1st to 15thNight
5%31333435%7%58%
1800
16th to endNight
8%32342447%8%49%
2054
August1st to 15thNight
7%31443447%8%50%
1996
16th to endNight
8%4145%345%5%5%51%
2213
September1st to 15thNight
11%41442446%8%45%
2270
16th to endNight
11%424424347%49%
2501
October1st to 15thNight
17%6%35%5%2345%7%39%
2700
16th to endNight
21%8%36%5%3445%5%30%
2880
November1st to 15thNight
17%7%35%5%35%45%6%36%
3178
16th to endNight
19%10%36%6%35%5%5%7%27%
3360
December1st to 15thNight
19%13%5%7%6%35%5%5%6%24%
3360
16th to endNight
20%12%5%9%7%35%5%45%20%
3584

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
62%311%15%6%
1969
16th to endDay
63%310%14%7%
2304
February1st to 15thDay
64%310%17%41
2117
16th to endDay
58%310%17%8%1
1883
March1st to 15thDay
55%311%19%8%
2475
16th to endDay
50%39%21%14%1
2640
April1st to 15thDay
53%310%19%12%
2658
16th to endDay
48%29%21%14%3
2879
May1st to 15thDay
47%410%23%13%
2965
16th to endDay
39%315%25%14%1
3294
June1st to 15thDay
39%411%26%15%1
3150
16th to endDay
38%413%26%15%
3150
July1st to 15thDay
31%5%12%30%18%2
3001
16th to endDay
38%5%15%25%13%1
3010
August1st to 15thDay
37%416%26%14%1
2864
16th to endDay
35%413%32%12%1
3029
September1st to 15thDay
40%5%13%26%12%
2678
16th to endDay
37%414%31%11%
2449
October1st to 15thDay
48%312%22%11%1
2250
16th to endDay
58%413%17%6%
2400
November1st to 15thDay
51%413%19%9%1
1996
16th to endDay
57%415%17%4
1920
December1st to 15thDay
64%312%15%4
1920
16th to endDay
65%411%15%3
2048
January1st to 15thNight
63%310%15%6%
3289
16th to endNight
60%210%17%7%
3328
February1st to 15thNight
61%39%17%6%
3067
16th to endNight
55%210%20%9%
2603
March1st to 15thNight
54%310%21%8%
2475
16th to endNight
45%28%23%16%2
2640
April1st to 15thNight
51%39%20%14%
2280
16th to endNight
43%39%22%17%3
2029
May1st to 15thNight
43%39%23%17%2
1976
16th to endNight
34%413%27%16%3
1881
June1st to 15thNight
37%410%25%19%2
1800
16th to endNight
35%313%26%19%1
1785
July1st to 15thNight
24%310%29%27%4
1720
16th to endNight
31%314%28%17%3
1948
August1st to 15thNight
29%316%33%14%2
1985
16th to endNight
33%312%33%16%1
2213
September1st to 15thNight
35%414%29%15%
2270
16th to endNight
34%311%34%14%
2501
October1st to 15thNight
44%310%26%14%
2700
16th to endNight
54%411%19%10%
2880
November1st to 15thNight
47%312%22%12%1
3178
16th to endNight
54%416%19%5%
3360
December1st to 15thNight
59%412%17%5%
3360
16th to endNight
64%412%13%5%
3584

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
15%18%34%17%10%1
201
16th to endDay
23%17%36%17%5%
288
February1st to 15thDay
23%15%43%14%2
270
16th to endDay
22%17%37%20%1
229
March1st to 15thDay
19%17%30%22%9%
450
16th to endDay
20%15%30%24%7%1
480
April1st to 15thDay
22%17%28%24%6%1
450
16th to endDay
20%16%27%19%10%4
439
May1st to 15thDay
22%13%25%21%10%6%
468
16th to endDay
14%9%25%27%17%5%
523
June1st to 15thDay
13%13%23%30%16%2
495
16th to endDay
13%9%20%28%21%6%
495
July1st to 15thDay
7%414%32%28%13%
485
16th to endDay
9%7%19%35%18%9%
518
August1st to 15thDay
10%6%16%28%24%14%
478
16th to endDay
12%6%19%28%20%14%
524
September1st to 15thDay
13%6%19%28%18%14%
495
16th to endDay
11%9%22%23%21%12%
494
October1st to 15thDay
21%11%28%21%12%5%
495
16th to endDay
25%14%29%22%8%
528
November1st to 15thDay
23%16%26%22%9%1
244
16th to endDay
25%12%36%18%6%1
180
December1st to 15thDay
21%15%34%22%5%
180
16th to endDay
25%16%35%18%3
192
January1st to 15thNight
21%23%28%20%6%
960
16th to endNight
19%19%32%23%5%
1024
February1st to 15thNight
22%22%32%19%3
944
16th to endNight
18%19%33%23%4
817
March1st to 15thNight
19%21%28%22%7%
900
16th to endNight
18%19%26%26%8%
960
April1st to 15thNight
18%19%30%25%5%
898
16th to endNight
16%20%23%27%10%1
693
May1st to 15thNight
17%15%21%29%13%2
626
16th to endNight
11%15%22%32%17%
471
June1st to 15thNight
11%16%22%34%13%
450
16th to endNight
7%14%17%37%22%
450
July1st to 15thNight
5%10%14%39%27%2
430
16th to endNight
8%14%14%38%21%3
628
August1st to 15thNight
8%8%9%41%27%3
665
16th to endNight
9%8%14%34%28%4
779
September1st to 15thNight
12%10%18%29%23%6%
900
16th to endNight
12%8%16%29%27%5%
897
October1st to 15thNight
19%10%23%27%17%2
900
16th to endNight
25%13%26%27%6%
960
November1st to 15thNight
19%16%24%27%10%1
940
16th to endNight
23%19%27%21%7%
960
December1st to 15thNight
25%20%28%20%4
960
16th to endNight
23%20%32%19%3
1024
Page generated at 2021-02-23 07:38:00. Version ac04

Copyright 2021 A. Danko


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