Sharbot Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sharbot Lake clear sky chart from 2005-11-05 to 2017-11-30.

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
28%
14999
14%
47797
8%
14970
36%
14970
17%
33371

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
14%
720
7%
2506
2%
716
20%
716
6%
2000
January16th to endNight
19%
768
12%
2596
5%
768
27%
768
11%
1954
February1st to 15thNight
15%
702
10%
2287
3%
701
24%
701
10%
1725
February16th to endNight
18%
631
15%
1968
5%
631
31%
631
14%
1417
March1st to 15thNight
18%
720
14%
2064
6%
720
26%
720
15%
1509
March16th to endNight
28%
768
21%
2058
9%
768
37%
768
23%
1392
April1st to 15thNight
20%
718
16%
1796
5%
718
26%
718
19%
1295
April16th to endNight
27%
656
18%
1736
7%
656
33%
656
22%
1206
May1st to 15thNight
34%
366
18%
1446
14%
366
45%
366
18%
923
May16th to endNight
33%
374
15%
1497
10%
374
47%
374
21%
885
June1st to 15thNight
34%
360
10%
1440
8%
360
44%
360
15%
947
June16th to endNight
42%
360
9%
1440
11%
360
49%
360
18%
908
July1st to 15thNight
49%
340
15%
1360
21%
340
55%
340
28%
741
July16th to endNight
53%
376
14%
1418
15%
354
60%
354
29%
788
August1st to 15thNight
46%
494
16%
1565
10%
492
52%
492
27%
954
August16th to endNight
49%
693
22%
1839
9%
693
56%
693
38%
1100
September1st to 15thNight
45%
720
19%
1800
8%
720
50%
720
32%
1177
September16th to endNight
48%
717
25%
1969
16%
717
53%
717
31%
1242
October1st to 15thNight
32%
720
17%
2160
11%
720
41%
720
21%
1480
October16th to endNight
21%
768
12%
2366
5%
768
30%
768
12%
1795
November1st to 15thNight
26%
760
18%
2550
12%
760
36%
760
16%
1774
November16th to endNight
18%
780
12%
2728
7%
780
26%
780
11%
2040
December1st to 15thNight
15%
720
7%
2520
2%
720
20%
720
8%
1969
December16th to endNight
12%
768
9%
2688
3%
768
19%
768
8%
2150

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
17%9%36%5%34446%32%
48619
Night
17%9%36%5%34446%34%
47967
Cloud CoverDay
18%8%36%5%34446%33%
48629
Night
17%9%36%5%34446%34%
47972
TransparencyDay
51%5%11%19%10%1
48307
Night
50%5%11%20%10%1
47797
SeeingDay
22%13%29%19%10%4
5695
Night
22%13%30%23%9%1
15002

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
20%15%6%7%5%3433424%
1432
16th to endDay
14%15%6%10%8%3433423%
1626
February1st to 15thDay
14%14%5%10%8%45%5%4422%
1575
16th to endDay
18%15%47%6%4444326%
1504
March1st to 15thDay
16%12%6%8%9%35%43327%
1882
16th to endDay
15%9%36%5%3333441%
2166
April1st to 15thDay
22%10%36%5%23336%33%
2152
16th to endDay
20%8%35%423335%37%
2235
May1st to 15thDay
19%8%27%5%34447%32%
2505
16th to endDay
14%6%26%5%35%45%6%37%
2618
June1st to 15thDay
22%6%26%4245%5%7%30%
2520
16th to endDay
16%6%26%5%35%5%5%7%33%
2520
July1st to 15thDay
12%6%25%5%45%6%6%8%36%
2520
16th to endDay
12%5%26%5%36%6%6%9%34%
2654
August1st to 15thDay
11%6%26%6%36%5%6%7%36%
2383
16th to endDay
13%425%5%35%5%6%7%39%
2351
September1st to 15thDay
15%6%25%433447%42%
2160
16th to endDay
16%5%24424346%45%
1987
October1st to 15thDay
21%8%25%5%2445%6%33%
1800
16th to endDay
26%9%46%6%34335%25%
1857
November1st to 15thDay
16%9%36%5%35%45%5%33%
1638
16th to endDay
22%13%5%6%5%25%336%26%
1558
December1st to 15thDay
22%15%6%6%7%34445%19%
1440
16th to endDay
22%16%6%7%6%2434420%
1536
January1st to 15thNight
20%13%5%9%7%45%34419%
2506
16th to endNight
13%15%5%9%6%34445%25%
2596
February1st to 15thNight
13%15%6%9%6%35%5%5%6%23%
2285
16th to endNight
14%13%5%6%5%34446%30%
1968
March1st to 15thNight
18%10%46%6%33435%32%
2052
16th to endNight
14%8%45%423445%42%
2058
April1st to 15thNight
21%8%35%434336%35%
1796
16th to endNight
17%7%35%5%2445%6%39%
1736
May1st to 15thNight
20%6%25%42246%5%38%
1446
16th to endNight
13%5%345%3445%8%42%
1495
June1st to 15thNight
16%7%35%6%35%447%34%
1440
16th to endNight
15%5%25%5%45%5%6%8%36%
1440
July1st to 15thNight
9%4245%3446%8%47%
1440
16th to endNight
9%41433447%9%47%
1514
August1st to 15thNight
10%5%25%43346%7%44%
1575
16th to endNight
9%325%32345%7%51%
1839
September1st to 15thNight
14%5%25%3235%48%45%
1800
16th to endNight
15%414423347%48%
1969
October1st to 15thNight
20%7%25%434446%36%
2160
16th to endNight
24%10%37%6%3335%5%27%
2366
November1st to 15thNight
18%9%35%434445%34%
2550
16th to endNight
22%11%37%6%35%445%26%
2728
December1st to 15thNight
20%15%5%8%5%24446%22%
2520
16th to endNight
23%15%48%6%35%425%20%
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%14%6%7%5%33335%24%
1432
16th to endDay
14%14%6%10%8%45%33423%
1626
February1st to 15thDay
14%14%5%10%8%45%5%35%22%
1575
16th to endDay
18%15%47%5%45%34326%
1504
March1st to 15thDay
17%12%6%8%9%35%43327%
1893
16th to endDay
15%8%46%424335%41%
2165
April1st to 15thDay
22%9%26%423335%33%
2152
16th to endDay
20%8%35%5%23336%37%
2235
May1st to 15thDay
19%7%26%5%34447%33%
2505
16th to endDay
15%6%26%5%35%5%5%6%38%
2618
June1st to 15thDay
23%6%25%4245%5%7%30%
2520
16th to endDay
17%6%25%5%45%5%5%8%33%
2520
July1st to 15thDay
13%5%245%35%6%6%8%36%
2520
16th to endDay
13%425%5%36%7%5%8%35%
2654
August1st to 15thDay
12%5%36%6%45%6%5%7%37%
2383
16th to endDay
14%415%5%345%6%7%39%
2351
September1st to 15thDay
15%6%245%33446%43%
2160
16th to endDay
16%5%24424346%45%
1987
October1st to 15thDay
21%7%25%5%2445%5%34%
1800
16th to endDay
26%9%37%5%34445%25%
1857
November1st to 15thDay
16%9%36%6%345%45%33%
1638
16th to endDay
22%12%5%6%424435%26%
1558
December1st to 15thDay
23%15%5%6%6%34445%20%
1440
16th to endDay
22%17%6%7%6%2444420%
1536
January1st to 15thNight
20%14%5%9%8%45%34420%
2506
16th to endNight
13%14%6%8%6%34445%26%
2596
February1st to 15thNight
13%14%6%9%5%35%5%5%6%24%
2278
16th to endNight
14%13%5%6%5%3445%6%30%
1968
March1st to 15thNight
18%11%46%6%33345%32%
2064
16th to endNight
15%8%45%424345%42%
2058
April1st to 15thNight
21%7%45%423345%36%
1796
16th to endNight
17%7%35%42445%5%39%
1736
May1st to 15thNight
20%6%25%5%2345%6%38%
1446
16th to endNight
13%6%25%424448%42%
1495
June1st to 15thNight
17%7%35%6%34447%34%
1440
16th to endNight
15%5%25%5%345%6%8%36%
1440
July1st to 15thNight
9%4245%3445%8%47%
1440
16th to endNight
9%32442446%9%48%
1514
August1st to 15thNight
10%5%245%3446%7%44%
1575
16th to endNight
9%325%42345%7%51%
1839
September1st to 15thNight
14%5%15%323448%45%
1800
16th to endNight
15%424423346%48%
1969
October1st to 15thNight
19%7%25%425%346%36%
2160
16th to endNight
24%10%37%6%33445%27%
2366
November1st to 15thNight
18%10%35%4345%45%34%
2550
16th to endNight
23%11%37%6%25%445%26%
2728
December1st to 15thNight
21%14%5%8%5%23445%22%
2520
16th to endNight
23%15%47%6%34435%20%
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
63%410%14%6%
1433
16th to endDay
64%5%7%12%8%1
1626
February1st to 15thDay
62%5%10%15%4
1577
16th to endDay
61%210%12%11%1
1504
March1st to 15thDay
62%311%14%7%1
1893
16th to endDay
47%38%19%15%5%
2166
April1st to 15thDay
53%46%18%14%2
2152
16th to endDay
48%47%20%16%3
2235
May1st to 15thDay
50%49%18%13%2
2505
16th to endDay
45%6%12%20%11%2
2622
June1st to 15thDay
51%7%10%20%10%
2520
16th to endDay
48%6%12%20%11%
2520
July1st to 15thDay
40%6%13%27%11%
2371
16th to endDay
44%8%13%22%9%
2487
August1st to 15thDay
43%7%14%23%10%
2369
16th to endDay
39%6%15%27%10%
2351
September1st to 15thDay
40%6%12%26%12%
2160
16th to endDay
39%5%11%31%11%
1987
October1st to 15thDay
49%5%10%23%10%
1800
16th to endDay
60%6%11%16%5%
1857
November1st to 15thDay
50%6%14%18%9%
1638
16th to endDay
59%6%12%12%8%1
1558
December1st to 15thDay
66%5%13%11%3
1440
16th to endDay
66%5%10%11%6%
1536
January1st to 15thNight
67%49%11%5%
2506
16th to endNight
59%5%9%16%8%
2596
February1st to 15thNight
59%5%12%16%5%
2287
16th to endNight
54%311%19%10%
1968
March1st to 15thNight
55%411%20%8%
2064
16th to endNight
44%49%21%16%3
2058
April1st to 15thNight
50%37%20%15%2
1796
16th to endNight
45%48%19%18%2
1736
May1st to 15thNight
46%48%20%15%4
1446
16th to endNight
39%6%14%22%15%2
1497
June1st to 15thNight
48%5%12%20%11%
1440
16th to endNight
44%6%13%21%13%
1440
July1st to 15thNight
32%5%12%28%18%1
1360
16th to endNight
32%6%18%26%15%
1418
August1st to 15thNight
36%7%16%26%12%
1565
16th to endNight
30%5%16%33%13%
1839
September1st to 15thNight
36%6%13%30%12%1
1800
16th to endNight
36%5%10%34%12%
1969
October1st to 15thNight
48%311%22%12%
2160
16th to endNight
58%5%11%16%7%
2366
November1st to 15thNight
50%5%13%18%11%1
2550
16th to endNight
59%411%17%5%
2728
December1st to 15thNight
63%5%14%12%3
2520
16th to endNight
67%5%10%11%6%
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%33%15%13%8%
60
16th to endDay
41%15%24%15%21
79
February1st to 15thDay
38%24%34%2
90
16th to endDay
32%20%28%12%4
163
March1st to 15thDay
26%17%31%18%4
270
16th to endDay
25%17%32%13%8%2
288
April1st to 15thDay
28%22%25%14%7%1
270
16th to endDay
24%19%27%16%8%4
270
May1st to 15thDay
28%14%27%15%9%3
288
16th to endDay
18%15%37%15%9%3
331
June1st to 15thDay
26%11%28%21%10%1
315
16th to endDay
17%11%33%24%10%1
315
July1st to 15thDay
16%9%29%25%14%4
305
16th to endDay
15%6%34%23%12%6%
326
August1st to 15thDay
14%430%30%14%6%
313
16th to endDay
15%7%26%23%14%11%
332
September1st to 15thDay
15%9%25%21%15%12%
315
16th to endDay
17%8%26%19%19%9%
314
October1st to 15thDay
26%12%28%18%8%4
315
16th to endDay
29%20%26%18%5%
320
November1st to 15thDay
21%11%31%25%7%2
202
16th to endDay
30%21%28%15%31
90
December1st to 15thDay
30%21%28%18%1
60
16th to endDay
43%26%26%3
64
January1st to 15thNight
29%20%27%17%4
720
16th to endNight
21%16%35%21%4
768
February1st to 15thNight
22%21%34%19%3
704
16th to endNight
22%17%36%18%4
631
March1st to 15thNight
28%15%32%21%1
720
16th to endNight
20%16%31%21%8%1
768
April1st to 15thNight
27%18%30%20%4
718
16th to endNight
22%16%30%19%10%
656
May1st to 15thNight
23%9%27%30%7%1
366
16th to endNight
14%8%38%25%11%
375
June1st to 15thNight
18%9%30%29%10%1
360
16th to endNight
16%5%30%33%13%
360
July1st to 15thNight
8%331%36%19%
340
16th to endNight
9%427%43%14%1
376
August1st to 15thNight
13%226%34%20%2
494
16th to endNight
9%5%29%31%20%2
693
September1st to 15thNight
16%428%27%20%2
720
16th to endNight
17%9%21%25%23%3
717
October1st to 15thNight
25%9%27%22%12%1
720
16th to endNight
30%13%27%21%6%
768
November1st to 15thNight
26%10%30%21%10%
760
16th to endNight
31%17%26%17%7%
780
December1st to 15thNight
28%20%29%18%2
720
16th to endNight
33%15%31%16%1
768
Page generated at 2017-12-01 12:13:44. Version ac04

Copyright 2017 A. Danko


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