This page made possible by the sponsorship of:
.

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 2020-06-03.

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%
18305
16%
57861
9%
18269
41%
18269
19%
38888

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%
897
11%
3083
4%
896
25%
896
10%
2350
January16th to endNight
17%
960
14%
3120
4%
960
29%
960
12%
2312
February1st to 15thNight
15%
881
11%
2872
3%
881
24%
881
11%
2186
February16th to endNight
21%
791
15%
2519
5%
791
33%
791
15%
1788
March1st to 15thNight
22%
900
16%
2475
6%
900
31%
900
16%
1793
March16th to endNight
27%
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
37%
626
18%
1976
10%
626
45%
626
21%
1263
May16th to endNight
44%
470
19%
1881
13%
470
57%
470
24%
1021
June1st to 15thNight
41%
425
15%
1701
13%
425
53%
425
19%
974
June16th to endNight
47%
420
15%
1667
16%
420
55%
420
23%
926
July1st to 15thNight
63%
400
20%
1600
27%
400
69%
400
36%
751
July16th to endNight
56%
585
17%
1809
17%
553
63%
553
33%
1002
August1st to 15thNight
63%
620
20%
1850
14%
617
67%
617
35%
1045
August16th to endNight
59%
726
24%
2064
14%
726
64%
726
34%
1211
September1st to 15thNight
55%
840
23%
2118
12%
840
59%
840
35%
1344
September16th to endNight
55%
837
24%
2334
17%
837
59%
837
33%
1413
October1st to 15thNight
41%
840
18%
2520
16%
840
47%
840
24%
1666
October16th to endNight
27%
896
17%
2688
9%
896
36%
896
17%
1936
November1st to 15thNight
33%
880
18%
2975
14%
880
41%
880
18%
2001
November16th to endNight
24%
900
12%
3150
5%
900
33%
900
13%
2224
December1st to 15thNight
18%
900
10%
3150
5%
900
25%
900
11%
2351
December16th to endNight
15%
960
9%
3360
3%
960
23%
960
9%
2599

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%8%36%6%35%5%5%7%34%
58535
Night
15%8%36%5%3445%6%36%
58042
Cloud CoverDay
14%7%36%6%35%5%5%7%33%
58545
Night
15%8%36%5%3445%6%35%
58046
TransparencyDay
48%412%22%11%1
58234
Night
48%311%22%12%1
57861
SeeingDay
17%11%25%24%14%6%
8723
Night
17%17%24%26%12%1
18312

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
17%12%5%10%7%35%5%5%6%22%
1844
16th to endDay
13%13%5%11%8%45%5%6%5%20%
2160
February1st to 15thDay
14%14%5%10%7%46%45%5%20%
1980
16th to endDay
16%12%5%8%6%3445%6%26%
1829
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
14%5%25%435%5%5%8%39%
2968
16th to endDay
12%4245%35%6%7%9%39%
2940
July1st to 15thDay
6%3245%36%6%6%9%45%
2940
16th to endDay
9%425%5%46%6%7%9%37%
2954
August1st to 15thDay
6%426%5%45%5%6%9%41%
2682
16th to endDay
9%5%245%345%48%44%
2827
September1st to 15thDay
13%5%25%5%35%5%5%8%40%
2500
16th to endDay
11%5%245%35%45%7%43%
2286
October1st to 15thDay
19%6%26%6%3445%6%34%
2100
16th to endDay
23%8%47%5%25%5%5%6%24%
2240
November1st to 15thDay
15%10%36%6%3445%7%31%
1869
16th to endDay
18%12%46%5%35%5%5%7%25%
1800
December1st to 15thDay
17%15%5%9%7%35%445%20%
1800
16th to endDay
19%11%5%10%7%45%5%5%5%19%
1920
January1st to 15thNight
19%13%5%8%6%35%5%45%22%
3083
16th to endNight
15%12%5%8%7%35%446%25%
3120
February1st to 15thNight
15%13%5%9%7%35%5%45%23%
2870
16th to endNight
14%10%49%6%35%45%6%29%
2519
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
12%425%43445%8%42%
1701
16th to endNight
9%5%246%245%6%7%43%
1667
July1st to 15thNight
5%31332435%8%58%
1680
16th to endNight
9%32442447%7%49%
1915
August1st to 15thNight
7%3145%35%46%7%51%
1861
16th to endNight
8%314425%5%5%5%51%
2064
September1st to 15thNight
11%42442446%7%46%
2118
16th to endNight
12%415%323447%49%
2334
October1st to 15thNight
18%6%25%42345%6%39%
2520
16th to endNight
19%8%36%6%35%445%32%
2688
November1st to 15thNight
18%7%35%5%35%45%6%34%
2975
16th to endNight
19%8%46%5%35%5%5%7%28%
3150
December1st to 15thNight
19%13%47%5%35%45%6%24%
3150
16th to endNight
20%11%6%9%7%35%445%20%
3360

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%410%8%3445%7%20%
1844
16th to endDay
13%13%5%11%8%45%5%6%6%19%
2160
February1st to 15thDay
15%13%6%10%8%45%445%20%
1980
16th to endDay
16%11%5%9%6%3445%6%26%
1829
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%35%5%6%8%39%
2968
16th to endDay
11%415%5%35%6%7%9%39%
2940
July1st to 15thDay
6%3245%36%6%7%9%45%
2940
16th to endDay
8%425%5%36%6%7%9%38%
2954
August1st to 15thDay
6%5%26%6%45%5%6%9%41%
2682
16th to endDay
9%5%25%5%3445%8%45%
2827
September1st to 15thDay
13%4345%25%5%5%8%39%
2500
16th to endDay
11%5%245%35%45%8%43%
2286
October1st to 15thDay
18%8%25%5%3435%7%35%
2100
16th to endDay
23%8%38%5%245%5%6%24%
2240
November1st to 15thDay
15%9%37%6%3445%7%31%
1869
16th to endDay
17%12%46%6%35%46%8%25%
1800
December1st to 15thDay
17%14%5%9%7%35%445%20%
1800
16th to endDay
19%11%5%10%7%46%5%5%419%
1920
January1st to 15thNight
20%12%49%6%35%445%21%
3083
16th to endNight
15%12%6%8%7%45%446%24%
3120
February1st to 15thNight
15%14%6%8%7%35%445%23%
2863
16th to endNight
14%10%49%6%45%45%6%29%
2519
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%
1701
16th to endNight
9%425%5%345%6%7%43%
1667
July1st to 15thNight
5%31333435%7%58%
1680
16th to endNight
8%323425%47%8%49%
1915
August1st to 15thNight
7%31443446%8%50%
1861
16th to endNight
8%4145%345%5%5%51%
2064
September1st to 15thNight
12%4143245%6%8%46%
2118
16th to endNight
11%42442435%7%49%
2334
October1st to 15thNight
17%6%35%5%23447%39%
2520
16th to endNight
20%8%36%5%34445%31%
2688
November1st to 15thNight
18%7%35%5%35%45%6%34%
2975
16th to endNight
19%9%36%5%35%5%5%7%27%
3150
December1st to 15thNight
19%12%5%7%5%35%5%5%6%24%
3150
16th to endNight
20%12%5%9%7%35%5%45%20%
3360

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%411%15%6%
1845
16th to endDay
64%39%14%7%
2160
February1st to 15thDay
64%311%16%3
1982
16th to endDay
58%311%17%8%1
1829
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
41%411%26%14%1
2968
16th to endDay
39%5%13%25%15%
2940
July1st to 15thDay
32%5%11%27%19%3
2791
16th to endDay
39%5%16%24%12%2
2797
August1st to 15thDay
37%417%25%14%1
2669
16th to endDay
35%413%31%13%1
2827
September1st to 15thDay
40%5%13%26%12%
2500
16th to endDay
39%414%30%10%
2286
October1st to 15thDay
48%311%22%11%1
2100
16th to endDay
57%414%17%6%
2240
November1st to 15thDay
52%413%19%7%1
1869
16th to endDay
56%415%17%4
1800
December1st to 15thDay
65%312%15%4
1800
16th to endDay
65%411%15%3
1920
January1st to 15thNight
63%310%15%7%
3083
16th to endNight
60%211%17%7%
3120
February1st to 15thNight
61%410%17%6%
2872
16th to endNight
55%211%21%9%
2519
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
38%410%25%18%2
1701
16th to endNight
36%313%25%18%1
1667
July1st to 15thNight
25%311%27%28%4
1600
16th to endNight
32%315%28%17%3
1809
August1st to 15thNight
30%416%32%14%1
1850
16th to endNight
33%311%33%17%1
2064
September1st to 15thNight
34%414%30%14%1
2118
16th to endNight
34%411%34%13%
2334
October1st to 15thNight
45%310%25%14%
2520
16th to endNight
53%411%20%9%
2688
November1st to 15thNight
49%412%21%11%1
2975
16th to endNight
53%416%19%5%
3150
December1st to 15thNight
59%413%17%5%
3150
16th to endNight
64%412%13%5%
3360

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
17%17%37%17%8%1
167
16th to endDay
25%16%37%15%5%
240
February1st to 15thDay
25%14%42%14%2
225
16th to endDay
22%17%36%21%
211
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
15%12%22%30%16%2
443
16th to endDay
14%10%21%28%21%4
435
July1st to 15thDay
7%5%15%30%26%14%
425
16th to endDay
9%8%19%33%19%10%
454
August1st to 15thDay
9%6%16%29%24%14%
418
16th to endDay
12%5%17%26%21%15%
460
September1st to 15thDay
12%417%28%20%16%
435
16th to endDay
12%9%19%22%21%14%
434
October1st to 15thDay
22%9%26%21%14%5%
435
16th to endDay
24%15%27%24%8%
464
November1st to 15thDay
24%17%26%20%10%1
207
16th to endDay
26%10%32%22%8%1
150
December1st to 15thDay
21%15%34%22%5%
150
16th to endDay
25%14%38%18%2
160
January1st to 15thNight
21%24%29%18%5%
900
16th to endNight
19%20%30%23%5%
960
February1st to 15thNight
22%22%31%19%3
884
16th to endNight
18%19%34%23%4
791
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
12%16%21%35%13%
425
16th to endNight
8%15%17%36%21%
420
July1st to 15thNight
5%10%14%39%26%2
400
16th to endNight
8%14%13%38%21%3
585
August1st to 15thNight
8%9%9%40%28%3
620
16th to endNight
9%8%13%34%28%4
726
September1st to 15thNight
11%10%16%29%24%7%
840
16th to endNight
12%9%15%28%28%6%
837
October1st to 15thNight
19%11%21%27%18%2
840
16th to endNight
24%14%26%28%6%
896
November1st to 15thNight
20%16%23%27%10%1
880
16th to endNight
22%19%26%22%7%1
900
December1st to 15thNight
25%21%28%20%4
900
16th to endNight
22%21%32%20%3
960
Page generated at 2020-06-04 03:18:58. Version ac04

Copyright 2020 A. Danko


Mississauga Clear Sky Chart |Charts Home