Orillia
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Orillia clear sky chart from 2005-11-05 to 2017-12-20.

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%
15120
12%
47801
8%
15087
38%
15087
16%
34789

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
13%
718
6%
2503
2%
716
17%
716
6%
2099
January16th to endNight
21%
768
8%
2496
4%
768
26%
768
9%
2039
February1st to 15thNight
18%
701
7%
2287
4%
701
22%
701
9%
1841
February16th to endNight
24%
631
10%
2030
6%
631
31%
631
13%
1530
March1st to 15thNight
24%
720
13%
1980
7%
720
30%
720
17%
1473
March16th to endNight
34%
768
19%
2112
11%
768
41%
768
25%
1439
April1st to 15thNight
29%
718
14%
1814
6%
718
33%
718
22%
1342
April16th to endNight
37%
552
18%
1632
10%
552
43%
552
23%
1124
May1st to 15thNight
46%
465
15%
1545
13%
465
51%
465
22%
1016
May16th to endNight
47%
374
15%
1497
14%
374
55%
374
23%
858
June1st to 15thNight
44%
360
10%
1425
11%
360
51%
360
19%
884
June16th to endNight
53%
360
11%
1260
12%
360
58%
360
24%
788
July1st to 15thNight
61%
340
16%
1254
21%
340
66%
340
32%
668
July16th to endNight
57%
455
15%
1491
16%
427
60%
427
27%
870
August1st to 15thNight
63%
539
16%
1609
12%
536
65%
536
32%
969
August16th to endNight
57%
618
19%
1764
11%
618
61%
618
32%
1108
September1st to 15thNight
51%
720
16%
1803
8%
720
54%
720
30%
1222
September16th to endNight
52%
717
21%
2007
15%
717
56%
717
29%
1296
October1st to 15thNight
33%
720
13%
2160
11%
720
38%
720
18%
1575
October16th to endNight
20%
768
11%
2304
5%
768
28%
768
11%
1816
November1st to 15thNight
29%
760
14%
2613
12%
760
34%
760
14%
1898
November16th to endNight
20%
780
8%
2730
5%
780
25%
780
8%
2219
December1st to 15thNight
12%
780
3%
2730
1%
780
14%
780
5%
2336
December16th to endNight
9%
788
7%
2755
2%
788
15%
788
5%
2379

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%9%46%6%35%45%6%32%
49033
Night
15%9%47%6%35%45%6%31%
47973
Cloud CoverDay
15%8%36%6%35%5%5%6%33%
49043
Night
15%9%47%6%3445%6%31%
47978
TransparencyDay
50%7%12%19%9%
48724
Night
52%7%12%17%9%
47801
SeeingDay
19%6%26%28%13%4
5894
Night
20%9%29%27%11%1
15126

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%14%7%9%8%34446%19%
1432
16th to endDay
13%16%8%11%7%34445%18%
1728
February1st to 15thDay
12%15%7%12%9%34445%19%
1575
16th to endDay
15%15%6%10%8%4444422%
1440
March1st to 15thDay
14%10%48%7%45%435%30%
1969
16th to endDay
14%8%36%6%24346%37%
2112
April1st to 15thDay
20%10%36%5%25%346%31%
2134
16th to endDay
18%8%35%423346%38%
2337
May1st to 15thDay
17%7%45%5%245%5%6%35%
2405
16th to endDay
12%5%25%5%35%45%7%42%
2618
June1st to 15thDay
17%6%25%5%2446%8%35%
2530
16th to endDay
14%5%25%5%35%5%5%9%36%
2700
July1st to 15thDay
9%425%5%45%46%9%43%
2628
16th to endDay
10%425%6%36%5%6%8%38%
2573
August1st to 15thDay
10%5%245%25%5%6%7%42%
2340
16th to endDay
9%6%25%5%445%6%8%42%
2426
September1st to 15thDay
16%6%26%5%34446%39%
2154
16th to endDay
15%5%245%34446%42%
1953
October1st to 15thDay
20%8%36%6%3435%5%31%
1800
16th to endDay
26%10%37%7%4444421%
1920
November1st to 15thDay
19%11%47%7%3445%7%24%
1571
16th to endDay
20%13%5%6%6%37%7%35%19%
1560
December1st to 15thDay
16%16%8%10%8%35%35%6%15%
1560
16th to endDay
20%16%7%9%7%35%5%45%14%
1568
January1st to 15thNight
18%14%7%11%8%4445%416%
2503
16th to endNight
15%14%7%10%9%45%5%45%17%
2496
February1st to 15thNight
11%16%7%11%8%45%45%5%18%
2285
16th to endNight
15%13%5%9%6%35%45%5%26%
2030
March1st to 15thNight
16%10%5%7%6%35%335%32%
1968
16th to endNight
14%8%36%5%23445%40%
2112
April1st to 15thNight
20%10%35%5%33346%33%
1814
16th to endNight
15%7%37%5%34446%37%
1632
May1st to 15thNight
16%7%25%5%2446%7%37%
1545
16th to endNight
12%424435%45%8%45%
1495
June1st to 15thNight
13%6%35%425%5%47%40%
1425
16th to endNight
9%7%16%5%345%5%9%40%
1260
July1st to 15thNight
6%42443435%6%54%
1329
16th to endNight
10%323425%5%6%9%45%
1593
August1st to 15thNight
6%414435%47%9%48%
1620
16th to endNight
9%4245%4445%6%49%
1764
September1st to 15thNight
13%42442445%7%43%
1803
16th to endNight
12%6%25%5%2445%6%45%
2007
October1st to 15thNight
19%6%35%5%35%5%47%32%
2160
16th to endNight
22%9%48%6%35%45%6%24%
2304
November1st to 15thNight
18%9%36%5%35%46%7%30%
2613
16th to endNight
20%11%5%8%6%45%5%5%6%20%
2730
December1st to 15thNight
18%14%6%10%7%45%45%5%15%
2730
16th to endNight
20%17%7%10%8%4444412%
2755

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%14%5%9%7%346%46%18%
1432
16th to endDay
14%16%6%10%8%445%45%18%
1728
February1st to 15thDay
12%14%7%12%9%4444420%
1575
16th to endDay
15%14%6%10%7%4444423%
1440
March1st to 15thDay
15%10%47%6%36%445%31%
1980
16th to endDay
14%7%36%6%35%446%38%
2111
April1st to 15thDay
19%9%46%5%25%446%32%
2134
16th to endDay
17%7%25%5%2335%6%39%
2337
May1st to 15thDay
16%6%36%5%245%5%6%36%
2405
16th to endDay
12%5%25%5%35%45%8%42%
2618
June1st to 15thDay
17%6%25%5%2445%8%36%
2530
16th to endDay
13%425%5%35%5%6%9%37%
2700
July1st to 15thDay
8%4246%35%5%7%9%43%
2628
16th to endDay
9%5%26%5%36%5%7%9%38%
2573
August1st to 15thDay
10%5%25%5%245%6%8%43%
2340
16th to endDay
9%4245%35%5%6%8%41%
2426
September1st to 15thDay
15%5%25%5%335%5%6%40%
2154
16th to endDay
14%5%25%5%35%445%43%
1953
October1st to 15thDay
20%8%36%6%35%445%31%
1800
16th to endDay
26%9%37%7%345%45%22%
1920
November1st to 15thDay
19%9%47%6%45%5%5%7%25%
1571
16th to endDay
21%12%5%8%5%36%6%46%18%
1560
December1st to 15thDay
17%14%7%11%8%35%446%14%
1560
16th to endDay
20%16%5%9%7%44446%14%
1568
January1st to 15thNight
18%14%6%11%8%44445%16%
2503
16th to endNight
15%15%6%10%8%35%5%45%18%
2496
February1st to 15thNight
11%16%7%10%8%35%5%5%5%19%
2278
16th to endNight
15%12%5%8%7%2445%6%26%
2030
March1st to 15thNight
17%9%47%7%35%335%33%
1980
16th to endNight
14%8%26%5%2345%5%40%
2112
April1st to 15thNight
19%10%35%5%3335%6%33%
1814
16th to endNight
14%6%36%6%24446%38%
1632
May1st to 15thNight
16%7%25%5%335%5%8%37%
1545
16th to endNight
10%5%33335%46%8%44%
1495
June1st to 15thNight
14%6%34435%448%40%
1425
16th to endNight
10%426%5%35%5%6%8%40%
1260
July1st to 15thNight
7%324425%446%54%
1329
16th to endNight
9%3145%25%6%5%9%45%
1593
August1st to 15thNight
6%4244346%5%8%48%
1620
16th to endNight
9%3245%34446%49%
1764
September1st to 15thNight
13%5%2443346%7%44%
1803
16th to endNight
13%5%25%424446%46%
2007
October1st to 15thNight
19%6%26%6%35%5%5%6%33%
2160
16th to endNight
22%9%46%7%35%446%25%
2304
November1st to 15thNight
18%8%47%5%35%45%7%30%
2613
16th to endNight
21%11%47%7%35%5%5%6%20%
2730
December1st to 15thNight
19%15%6%10%7%45%5%45%15%
2730
16th to endNight
21%17%6%11%7%3434413%
2755

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
66%6%12%9%4
1433
16th to endDay
67%5%9%9%7%
1728
February1st to 15thDay
67%6%9%12%3
1577
16th to endDay
64%5%8%13%7%
1440
March1st to 15thDay
54%7%14%16%6%
1980
16th to endDay
46%5%10%18%16%2
2112
April1st to 15thDay
52%5%9%19%11%
2134
16th to endDay
46%49%22%14%1
2337
May1st to 15thDay
47%6%10%20%13%1
2405
16th to endDay
40%7%13%23%13%1
2622
June1st to 15thDay
45%6%13%24%10%
2530
16th to endDay
42%8%16%20%12%
2700
July1st to 15thDay
34%8%14%26%14%1
2475
16th to endDay
41%8%13%25%10%1
2412
August1st to 15thDay
37%8%17%21%12%1
2327
16th to endDay
38%8%16%26%9%
2426
September1st to 15thDay
43%6%14%24%9%
2154
16th to endDay
43%7%12%28%8%
1953
October1st to 15thDay
54%5%11%18%8%
1800
16th to endDay
63%7%13%11%4
1920
November1st to 15thDay
58%8%12%14%6%
1571
16th to endDay
65%10%12%9%2
1560
December1st to 15thDay
71%8%12%6%1
1560
16th to endDay
71%7%9%8%3
1568
January1st to 15thNight
70%6%10%8%3
2503
16th to endNight
66%7%9%10%5%
2496
February1st to 15thNight
65%6%11%12%3
2287
16th to endNight
57%6%13%15%6%
2030
March1st to 15thNight
55%5%12%18%7%
1980
16th to endNight
44%5%10%21%16%1
2112
April1st to 15thNight
52%49%20%12%1
1814
16th to endNight
45%6%9%17%18%2
1632
May1st to 15thNight
44%6%12%16%17%2
1545
16th to endNight
37%6%14%24%15%1
1497
June1st to 15thNight
42%6%11%24%13%
1425
16th to endNight
39%7%15%22%14%
1260
July1st to 15thNight
28%6%12%28%22%
1254
16th to endNight
34%7%13%29%14%
1491
August1st to 15thNight
31%8%19%25%14%
1609
16th to endNight
34%7%15%26%14%1
1764
September1st to 15thNight
38%9%15%24%11%1
1803
16th to endNight
38%6%12%30%11%
2007
October1st to 15thNight
50%8%11%19%10%
2160
16th to endNight
61%6%11%14%5%
2304
November1st to 15thNight
54%6%14%15%7%1
2613
16th to endNight
63%10%11%11%2
2730
December1st to 15thNight
70%8%11%6%1
2730
16th to endNight
74%5%7%8%2
2755

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
20%16%46%11%5%
60
16th to endDay
41%430%18%5%
96
February1st to 15thDay
28%12%40%18%
90
16th to endDay
29%13%31%25%
87
March1st to 15thDay
21%11%34%27%4
270
16th to endDay
22%5%35%22%12%1
288
April1st to 15thDay
21%6%36%25%8%1
270
16th to endDay
21%7%30%21%13%5%
270
May1st to 15thDay
26%325%28%12%4
288
16th to endDay
16%326%34%16%3
331
June1st to 15thDay
21%423%32%15%1
325
16th to endDay
15%326%37%13%2
495
July1st to 15thDay
11%321%38%17%6%
409
16th to endDay
8%27%35%19%7%
326
August1st to 15thDay
15%115%34%22%10%
313
16th to endDay
15%416%27%25%11%
332
September1st to 15thDay
16%319%28%20%12%
315
16th to endDay
15%5%21%22%24%9%
314
October1st to 15thDay
23%9%26%25%10%4
315
16th to endDay
27%16%29%21%4
336
November1st to 15thDay
22%18%25%25%7%
112
16th to endDay
26%20%36%15%1
90
December1st to 15thDay
18%25%34%16%4
90
16th to endDay
31%29%36%2
72
January1st to 15thNight
26%17%31%19%4
720
16th to endNight
22%10%32%28%5%1
768
February1st to 15thNight
20%8%39%26%4
704
16th to endNight
23%8%34%26%6%
631
March1st to 15thNight
22%11%34%27%4
720
16th to endNight
19%6%32%28%12%
768
April1st to 15thNight
26%7%30%29%6%
718
16th to endNight
17%7%30%29%13%
552
May1st to 15thNight
20%321%35%16%2
465
16th to endNight
13%227%37%18%
375
June1st to 15thNight
15%5%25%36%15%1
360
16th to endNight
12%323%41%17%1
360
July1st to 15thNight
7%319%46%20%2
340
16th to endNight
11%222%38%23%
455
August1st to 15thNight
8%317%40%26%3
539
16th to endNight
11%221%33%26%2
618
September1st to 15thNight
16%422%28%21%5%
720
16th to endNight
16%5%19%31%19%7%
717
October1st to 15thNight
22%7%30%26%10%2
720
16th to endNight
28%15%30%20%5%
768
November1st to 15thNight
23%12%30%22%10%1
760
16th to endNight
27%16%30%19%5%
780
December1st to 15thNight
27%21%31%15%2
780
16th to endNight
29%14%36%15%21
788
Page generated at 2017-12-21 07:04:47. Version ac04

Copyright 2017 A. Danko


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