Lake of Bays
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake of Bays clear sky chart from 2005-11-05 to 2017-09-18.

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
29%
14693
12%
46562
8%
14661
34%
14661
15%
34311

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
11%
719
5%
2506
2%
716
15%
716
5%
2117
January16th to endNight
19%
768
10%
2526
5%
768
25%
768
9%
2040
February1st to 15thNight
15%
702
8%
2287
3%
701
21%
701
8%
1865
February16th to endNight
18%
631
10%
2039
4%
631
26%
631
10%
1578
March1st to 15thNight
19%
720
12%
1985
5%
720
25%
720
14%
1516
March16th to endNight
31%
768
19%
2112
10%
768
38%
768
23%
1459
April1st to 15thNight
22%
718
14%
1800
5%
718
27%
718
18%
1369
April16th to endNight
31%
558
18%
1638
10%
558
37%
558
21%
1141
May1st to 15thNight
38%
436
16%
1516
13%
436
45%
436
20%
994
May16th to endNight
39%
374
13%
1497
11%
374
49%
374
20%
890
June1st to 15thNight
37%
360
9%
1405
8%
360
43%
360
16%
922
June16th to endNight
47%
360
10%
1260
10%
360
51%
360
20%
824
July1st to 15thNight
55%
340
15%
1240
19%
340
59%
340
29%
699
July16th to endNight
52%
418
14%
1457
15%
393
55%
393
25%
868
August1st to 15thNight
56%
539
15%
1609
12%
536
59%
536
28%
1028
August16th to endNight
52%
621
17%
1767
9%
621
56%
621
30%
1115
September1st to 15thNight
44%
720
14%
1800
7%
720
47%
720
29%
1229
September16th to endNight
45%
669
19%
1869
13%
669
49%
669
27%
1231
October1st to 15thNight
30%
660
15%
1980
10%
660
38%
660
18%
1421
October16th to endNight
18%
704
9%
2112
4%
704
24%
704
9%
1725
November1st to 15thNight
27%
700
14%
2429
12%
700
33%
700
14%
1755
November16th to endNight
19%
720
9%
2520
5%
720
24%
720
8%
2041
December1st to 15thNight
12%
720
4%
2520
2%
720
15%
720
5%
2189
December16th to endNight
10%
768
7%
2688
3%
768
15%
768
5%
2295

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
18%10%47%5%34446%29%
48233
Night
18%12%47%5%24445%30%
46730
Cloud CoverDay
18%10%47%5%34446%29%
48243
Night
18%12%47%5%34445%30%
46735
TransparencyDay
55%6%10%17%9%
47919
Night
55%5%10%17%9%
46562
SeeingDay
24%12%28%21%9%3
5650
Night
24%11%28%24%10%1
14697

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
21%17%9%10%6%2323417%
1432
16th to endDay
13%19%8%10%7%44435%18%
1695
February1st to 15thDay
12%18%8%14%8%34335%18%
1575
16th to endDay
15%17%7%11%5%3433422%
1434
March1st to 15thDay
16%12%48%7%45%45%5%25%
1963
16th to endDay
13%9%47%5%35%346%36%
2112
April1st to 15thDay
22%11%45%424345%30%
2147
16th to endDay
20%10%25%323335%37%
2331
May1st to 15thDay
20%8%35%5%35%447%31%
2433
16th to endDay
15%7%25%5%245%5%7%37%
2618
June1st to 15thDay
22%7%35%5%2445%7%29%
2550
16th to endDay
18%6%245%35%5%5%8%32%
2700
July1st to 15thDay
15%5%25%5%35%45%8%37%
2643
16th to endDay
13%5%26%6%35%46%9%34%
2611
August1st to 15thDay
14%5%37%6%36%5%47%35%
2340
16th to endDay
15%5%25%5%35%5%5%7%35%
2421
September1st to 15thDay
20%6%26%5%3335%6%36%
2160
16th to endDay
19%6%25%32445%5%39%
1813
October1st to 15thDay
26%8%36%5%23335%30%
1650
16th to endDay
35%11%26%5%23345%19%
1760
November1st to 15thDay
21%10%47%7%245%36%26%
1429
16th to endDay
24%17%6%9%5%3434416%
1440
December1st to 15thDay
21%23%7%10%6%2423414%
1440
16th to endDay
20%23%7%10%5%2334414%
1536
January1st to 15thNight
20%19%7%11%7%2324414%
2506
16th to endNight
14%17%8%11%7%34435%20%
2526
February1st to 15thNight
12%17%7%12%8%45%44418%
2285
16th to endNight
16%14%8%9%6%3444423%
2039
March1st to 15thNight
17%12%5%7%6%3434429%
1973
16th to endNight
14%9%46%42444440%
2112
April1st to 15thNight
22%12%445%2434431%
1800
16th to endNight
18%9%345%24447%35%
1638
May1st to 15thNight
19%7%15%42435%8%36%
1516
16th to endNight
12%5%25%4245%6%8%41%
1495
June1st to 15thNight
17%7%35%5%2445%7%35%
1405
16th to endNight
15%6%25%5%345%6%7%38%
1260
July1st to 15thNight
10%41442345%6%50%
1314
16th to endNight
11%5%24425%5%5%8%43%
1556
August1st to 15thNight
11%425%4245%47%45%
1620
16th to endNight
11%5%15%425%45%7%46%
1767
September1st to 15thNight
15%6%2442346%7%41%
1800
16th to endNight
17%5%24323336%44%
1869
October1st to 15thNight
22%8%34433446%34%
1980
16th to endNight
30%12%36%5%2343422%
2112
November1st to 15thNight
21%11%36%423446%30%
2429
16th to endNight
24%16%5%6%6%3443420%
2520
December1st to 15thNight
22%22%7%9%5%2433412%
2520
16th to endNight
22%19%8%10%6%2334414%
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
21%18%8%11%6%2233418%
1432
16th to endDay
13%18%8%11%8%4434418%
1695
February1st to 15thDay
12%18%8%14%9%33335%18%
1575
16th to endDay
15%17%8%10%7%3433421%
1434
March1st to 15thDay
16%11%5%8%7%45%35%5%25%
1974
16th to endDay
12%9%46%6%35%435%36%
2111
April1st to 15thDay
23%11%35%424345%30%
2147
16th to endDay
19%10%25%423345%38%
2331
May1st to 15thDay
19%9%36%5%34347%31%
2433
16th to endDay
15%7%35%5%345%5%7%38%
2618
June1st to 15thDay
22%8%36%5%2445%7%29%
2550
16th to endDay
18%6%35%435%5%5%8%32%
2700
July1st to 15thDay
14%6%35%5%35%45%8%37%
2643
16th to endDay
14%5%36%6%36%46%9%34%
2611
August1st to 15thDay
14%7%26%6%45%5%5%6%35%
2340
16th to endDay
14%6%26%6%45%5%6%8%35%
2421
September1st to 15thDay
20%7%25%5%34346%36%
2160
16th to endDay
19%6%25%434345%39%
1813
October1st to 15thDay
26%8%36%6%23336%30%
1650
16th to endDay
34%11%26%6%23345%18%
1760
November1st to 15thDay
21%12%38%6%33445%26%
1429
16th to endDay
24%17%7%8%5%33345%16%
1440
December1st to 15thDay
21%21%8%11%6%2323413%
1440
16th to endDay
20%24%7%10%5%2333414%
1536
January1st to 15thNight
20%19%8%11%7%3433414%
2506
16th to endNight
14%17%8%10%7%44335%20%
2526
February1st to 15thNight
12%16%7%12%8%35%35%5%18%
2278
16th to endNight
16%15%6%10%6%3443423%
2039
March1st to 15thNight
17%13%5%7%6%3424429%
1985
16th to endNight
14%9%46%413445%39%
2112
April1st to 15thNight
22%12%5%45%33335%31%
1800
16th to endNight
19%8%25%434447%35%
1638
May1st to 15thNight
19%7%25%32435%8%36%
1516
16th to endNight
13%5%25%425%46%8%40%
1495
June1st to 15thNight
17%7%35%5%3446%6%35%
1405
16th to endNight
14%7%15%5%35%5%6%7%37%
1260
July1st to 15thNight
10%43442345%6%50%
1314
16th to endNight
10%5%25%43445%8%44%
1556
August1st to 15thNight
11%425%4245%6%7%45%
1620
16th to endNight
10%5%245%2446%7%46%
1767
September1st to 15thNight
15%7%15%42445%8%41%
1800
16th to endNight
18%5%24423345%44%
1869
October1st to 15thNight
22%8%35%324446%34%
1980
16th to endNight
29%13%46%5%2343322%
2112
November1st to 15thNight
21%11%36%42435%6%30%
2429
16th to endNight
24%16%5%6%6%3434420%
2520
December1st to 15thNight
22%22%7%9%5%2443413%
2520
16th to endNight
22%19%8%11%6%2323414%
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
71%39%10%5%
1433
16th to endDay
69%47%9%8%1
1695
February1st to 15thDay
70%48%11%4
1577
16th to endDay
67%37%12%8%
1434
March1st to 15thDay
59%6%12%14%6%
1974
16th to endDay
49%49%17%14%3
2112
April1st to 15thDay
56%5%8%17%11%1
2147
16th to endDay
49%47%21%14%2
2331
May1st to 15thDay
51%5%10%18%12%1
2433
16th to endDay
44%7%12%20%13%2
2622
June1st to 15thDay
53%6%10%20%9%
2550
16th to endDay
47%8%14%18%10%1
2700
July1st to 15thDay
41%7%12%25%12%1
2488
16th to endDay
45%7%14%22%9%
2447
August1st to 15thDay
47%8%13%19%10%
2327
16th to endDay
45%8%13%24%7%
2421
September1st to 15thDay
48%5%12%22%9%
2160
16th to endDay
45%7%11%26%8%
1813
October1st to 15thDay
56%411%17%9%
1650
16th to endDay
66%7%9%11%5%
1760
November1st to 15thDay
58%7%12%14%6%
1429
16th to endDay
71%5%7%10%31
1440
December1st to 15thDay
75%5%8%7%2
1440
16th to endDay
74%46%9%4
1536
January1st to 15thNight
74%48%7%3
2506
16th to endNight
66%5%6%11%8%1
2526
February1st to 15thNight
68%5%9%11%5%
2287
16th to endNight
63%49%15%6%
2039
March1st to 15thNight
59%312%15%8%
1985
16th to endNight
45%5%9%20%16%2
2112
April1st to 15thNight
56%37%18%12%1
1800
16th to endNight
48%5%8%19%16%1
1638
May1st to 15thNight
45%5%11%18%15%2
1516
16th to endNight
40%6%15%22%13%1
1497
June1st to 15thNight
46%7%12%19%13%
1405
16th to endNight
43%7%13%23%11%
1260
July1st to 15thNight
32%7%11%29%18%
1240
16th to endNight
37%6%14%27%13%
1457
August1st to 15thNight
36%8%16%26%11%
1609
16th to endNight
35%7%16%28%10%1
1767
September1st to 15thNight
40%7%17%23%10%
1800
16th to endNight
41%5%13%29%9%
1869
October1st to 15thNight
50%6%11%19%11%
1980
16th to endNight
66%6%9%12%5%
2112
November1st to 15thNight
53%6%13%17%7%
2429
16th to endNight
67%6%9%12%3
2520
December1st to 15thNight
75%6%7%8%2
2520
16th to endNight
74%46%7%5%
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
30%21%36%10%1
60
16th to endDay
40%13%28%13%4
91
February1st to 15thDay
30%30%32%7%
90
16th to endDay
38%16%34%10%
93
March1st to 15thDay
23%20%32%19%31
270
16th to endDay
20%15%33%19%9%2
288
April1st to 15thDay
25%18%26%18%9%1
270
16th to endDay
27%17%25%15%9%4
270
May1st to 15thDay
32%7%26%20%8%5%
288
16th to endDay
22%13%35%15%10%3
331
June1st to 15thDay
24%12%30%22%9%1
345
16th to endDay
19%12%34%22%8%2
495
July1st to 15thDay
17%8%30%27%12%3
422
16th to endDay
15%10%26%29%11%6%
326
August1st to 15thDay
19%323%31%12%8%
313
16th to endDay
21%6%19%25%17%9%
332
September1st to 15thDay
20%7%22%24%16%8%
315
16th to endDay
19%7%28%22%15%6%
262
October1st to 15thDay
27%13%25%21%9%3
255
16th to endDay
41%13%26%15%3
272
November1st to 15thDay
26%15%30%20%6%
78
16th to endDay
45%16%26%10%1
60
December1st to 15thDay
33%23%26%15%1
60
16th to endDay
31%42%21%31
64
January1st to 15thNight
31%18%29%16%3
720
16th to endNight
23%13%35%19%7%1
768
February1st to 15thNight
22%19%32%20%5%
704
16th to endNight
25%17%31%19%5%
631
March1st to 15thNight
24%18%31%20%3
720
16th to endNight
19%12%30%24%10%1
768
April1st to 15thNight
27%14%31%21%5%
718
16th to endNight
23%10%29%25%10%
558
May1st to 15thNight
25%5%26%27%13%1
436
16th to endNight
15%6%34%33%9%
375
June1st to 15thNight
20%8%28%31%11%
360
16th to endNight
18%6%21%42%10%
360
July1st to 15thNight
10%323%44%16%
340
16th to endNight
12%325%38%19%
418
August1st to 15thNight
13%317%37%23%3
539
16th to endNight
13%5%23%32%22%2
621
September1st to 15thNight
18%427%27%17%4
720
16th to endNight
20%6%23%27%19%2
669
October1st to 15thNight
26%9%28%22%10%1
660
16th to endNight
35%13%28%17%5%
704
November1st to 15thNight
26%14%27%21%10%
700
16th to endNight
34%12%27%18%6%
720
December1st to 15thNight
32%20%29%13%3
720
16th to endNight
32%16%29%16%31
768
Page generated at 2017-09-19 07:32:32. Version ac04

Copyright 2017 A. Danko


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