Millsite Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Millsite Lake clear sky chart from 2005-11-05 to 2017-12-02.

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%
15040
12%
47812
8%
15009
34%
15009
15%
34828

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%
720
6%
2506
3%
716
17%
716
5%
2085
January16th to endNight
19%
768
8%
2616
5%
768
25%
768
9%
2066
February1st to 15thNight
13%
704
8%
2287
4%
701
20%
701
8%
1887
February16th to endNight
19%
631
11%
1936
5%
631
26%
631
10%
1523
March1st to 15thNight
19%
720
13%
2097
7%
720
26%
720
14%
1579
March16th to endNight
26%
768
17%
2034
8%
768
33%
768
19%
1471
April1st to 15thNight
22%
718
16%
1796
5%
718
27%
718
19%
1328
April16th to endNight
28%
687
16%
1767
6%
687
33%
687
22%
1251
May1st to 15thNight
36%
360
17%
1440
16%
360
44%
360
16%
950
May16th to endNight
35%
374
14%
1497
10%
374
44%
374
17%
947
June1st to 15thNight
36%
360
11%
1440
12%
360
45%
360
16%
963
June16th to endNight
40%
360
10%
1440
12%
360
47%
360
19%
894
July1st to 15thNight
47%
340
14%
1360
17%
340
55%
340
24%
780
July16th to endNight
52%
376
14%
1418
14%
354
56%
354
25%
797
August1st to 15thNight
50%
467
13%
1538
11%
465
54%
465
22%
973
August16th to endNight
52%
726
21%
1872
11%
726
56%
726
37%
1170
September1st to 15thNight
49%
720
16%
1800
8%
720
51%
720
31%
1215
September16th to endNight
49%
717
24%
1955
17%
717
54%
717
32%
1253
October1st to 15thNight
31%
720
16%
2160
12%
720
37%
720
19%
1525
October16th to endNight
21%
768
9%
2388
5%
768
27%
768
11%
1866
November1st to 15thNight
28%
760
14%
2501
12%
760
32%
760
15%
1779
November16th to endNight
22%
780
12%
2730
8%
780
27%
780
10%
2104
December1st to 15thNight
13%
728
5%
2546
2%
728
17%
728
6%
2145
December16th to endNight
11%
768
6%
2688
3%
768
14%
768
5%
2277

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
19%9%36%5%3445%6%32%
48646
Night
19%10%46%5%24446%31%
47981
Cloud CoverDay
19%9%36%5%34446%32%
48655
Night
19%10%47%5%34445%30%
47987
TransparencyDay
53%5%11%19%9%1
48333
Night
55%411%18%9%1
47812
SeeingDay
24%13%27%19%10%3
5766
Night
26%12%27%23%9%
15041

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
23%15%5%9%6%2444419%
1432
16th to endDay
17%16%5%9%7%45%44419%
1605
February1st to 15thDay
16%17%6%10%8%44445%17%
1575
16th to endDay
19%14%48%6%3443423%
1536
March1st to 15thDay
19%13%6%10%6%3433325%
1853
16th to endDay
21%8%35%41433438%
2189
April1st to 15thDay
23%10%45%424235%33%
2152
16th to endDay
21%8%235%24446%36%
2204
May1st to 15thDay
20%6%35%5%2445%6%35%
2511
16th to endDay
17%5%35%43446%8%37%
2618
June1st to 15thDay
24%5%25%425%45%7%31%
2520
16th to endDay
19%5%24435%46%9%34%
2520
July1st to 15thDay
13%425%4246%6%8%40%
2520
16th to endDay
13%5%245%35%5%6%9%38%
2654
August1st to 15thDay
13%5%35%435%5%6%8%37%
2409
16th to endDay
12%5%14425%5%6%8%42%
2318
September1st to 15thDay
18%5%24423447%42%
2160
16th to endDay
17%423323446%46%
2004
October1st to 15thDay
21%8%35%5%33446%34%
1800
16th to endDay
26%10%36%5%24345%25%
1836
November1st to 15thDay
16%9%35%6%45%46%6%32%
1683
16th to endDay
20%13%5%8%6%34445%23%
1560
December1st to 15thDay
23%17%5%8%6%35%335%15%
1451
16th to endDay
25%18%6%7%7%4433315%
1536
January1st to 15thNight
21%18%5%10%6%25%44416%
2506
16th to endNight
14%17%6%8%6%45%43422%
2616
February1st to 15thNight
17%16%7%12%7%3433419%
2285
16th to endNight
18%11%6%9%8%24446%23%
1936
March1st to 15thNight
21%12%5%6%5%2333430%
2084
16th to endNight
20%9%46%423235%38%
2034
April1st to 15thNight
24%7%35%32335%6%33%
1796
16th to endNight
19%6%34424445%38%
1767
May1st to 15thNight
22%6%25%424437%35%
1440
16th to endNight
14%6%345%35%5%46%40%
1495
June1st to 15thNight
21%6%25%4245%6%8%31%
1440
16th to endNight
16%4145%35%5%6%8%37%
1440
July1st to 15thNight
10%424435%5%6%8%44%
1440
16th to endNight
10%5%24325%5%6%10%43%
1514
August1st to 15thNight
12%5%35%4345%7%8%39%
1548
16th to endNight
11%4245%2445%8%47%
1872
September1st to 15thNight
16%4245%23347%45%
1800
16th to endNight
15%315%42435%7%46%
1955
October1st to 15thNight
21%7%25%5%24346%34%
2160
16th to endNight
26%9%47%6%24445%24%
2388
November1st to 15thNight
21%9%35%42445%5%32%
2501
16th to endNight
23%14%38%4345%45%23%
2730
December1st to 15thNight
23%18%5%9%6%3433417%
2546
16th to endNight
25%18%6%8%6%3433415%
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
22%16%5%9%7%3444319%
1432
16th to endDay
16%17%5%9%9%4444319%
1605
February1st to 15thDay
16%17%6%11%8%3444417%
1575
16th to endDay
19%15%5%9%6%35%33423%
1536
March1st to 15thDay
20%13%6%10%5%3433325%
1863
16th to endDay
21%9%35%42433438%
2188
April1st to 15thDay
24%11%35%423335%33%
2152
16th to endDay
21%8%2443445%5%36%
2204
May1st to 15thDay
20%6%35%5%235%46%35%
2511
16th to endDay
17%6%25%42446%7%37%
2618
June1st to 15thDay
24%6%25%42445%7%30%
2520
16th to endDay
19%6%245%25%45%8%34%
2520
July1st to 15thDay
13%425%4345%6%8%40%
2520
16th to endDay
13%5%245%35%5%6%8%37%
2654
August1st to 15thDay
13%6%25%6%345%5%8%37%
2409
16th to endDay
12%4244346%6%8%41%
2318
September1st to 15thDay
18%5%24424347%42%
2160
16th to endDay
17%5%24323346%45%
2004
October1st to 15thDay
23%7%25%433446%33%
1800
16th to endDay
27%11%35%5%33445%25%
1836
November1st to 15thDay
16%9%26%6%4445%6%31%
1683
16th to endDay
21%13%5%8%5%25%44423%
1560
December1st to 15thDay
24%18%5%7%7%24435%15%
1451
16th to endDay
26%18%6%7%6%35%32314%
1536
January1st to 15thNight
20%19%6%10%6%3433416%
2506
16th to endNight
14%18%5%9%6%4434422%
2616
February1st to 15thNight
17%16%6%13%6%3443319%
2278
16th to endNight
18%12%6%9%7%43346%22%
1936
March1st to 15thNight
22%12%5%7%5%2333430%
2097
16th to endNight
20%8%46%5%2323438%
2034
April1st to 15thNight
24%8%35%42335%5%33%
1796
16th to endNight
19%7%24424436%38%
1767
May1st to 15thNight
21%7%25%5%24446%35%
1440
16th to endNight
14%6%25%5%345%5%7%38%
1495
June1st to 15thNight
21%5%25%435%45%8%32%
1440
16th to endNight
15%4245%36%46%9%37%
1440
July1st to 15thNight
11%424425%5%6%7%44%
1440
16th to endNight
11%424425%5%7%10%42%
1514
August1st to 15thNight
13%5%25%4346%6%8%38%
1548
16th to endNight
11%41433446%8%47%
1872
September1st to 15thNight
17%425%423447%45%
1800
16th to endNight
15%315%42435%6%46%
1955
October1st to 15thNight
22%8%25%424345%34%
2160
16th to endNight
27%9%36%7%24445%24%
2388
November1st to 15thNight
20%10%35%434445%32%
2501
16th to endNight
23%13%5%6%5%23445%24%
2730
December1st to 15thNight
23%19%5%9%6%3433316%
2546
16th to endNight
25%19%6%8%6%3333415%
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
70%49%11%4
1433
16th to endDay
68%48%10%7%
1605
February1st to 15thDay
70%47%13%4
1577
16th to endDay
66%39%11%8%
1536
March1st to 15thDay
64%39%13%6%1
1863
16th to endDay
51%39%16%15%4
2189
April1st to 15thDay
55%37%19%12%2
2152
16th to endDay
49%5%7%19%14%3
2204
May1st to 15thDay
49%5%8%21%13%1
2511
16th to endDay
45%5%13%22%12%1
2622
June1st to 15thDay
53%5%11%19%10%
2520
16th to endDay
47%6%12%22%11%
2520
July1st to 15thDay
39%6%12%27%12%
2371
16th to endDay
42%7%15%23%10%
2487
August1st to 15thDay
44%7%15%22%9%
2395
16th to endDay
38%7%14%28%10%
2318
September1st to 15thDay
43%411%26%13%1
2160
16th to endDay
40%411%29%13%
2004
October1st to 15thDay
51%5%11%21%9%
1800
16th to endDay
61%413%14%4
1836
November1st to 15thDay
51%7%13%18%6%1
1683
16th to endDay
64%5%10%12%6%
1560
December1st to 15thDay
71%6%9%9%2
1451
16th to endDay
76%47%7%3
1536
January1st to 15thNight
72%48%10%3
2506
16th to endNight
66%48%13%6%
2616
February1st to 15thNight
70%38%12%4
2287
16th to endNight
64%49%14%7%
1936
March1st to 15thNight
59%210%19%6%
2097
16th to endNight
52%38%17%14%2
2034
April1st to 15thNight
52%39%18%14%
1796
16th to endNight
47%5%10%18%15%2
1767
May1st to 15thNight
49%48%18%14%3
1440
16th to endNight
45%6%12%20%13%2
1497
June1st to 15thNight
49%5%13%21%9%
1440
16th to endNight
42%6%13%22%14%
1440
July1st to 15thNight
35%7%11%29%13%1
1360
16th to endNight
35%5%17%25%13%1
1418
August1st to 15thNight
41%7%16%23%11%
1538
16th to endNight
33%5%13%34%12%
1872
September1st to 15thNight
39%6%12%28%12%1
1800
16th to endNight
37%410%31%14%
1955
October1st to 15thNight
51%410%22%10%
2160
16th to endNight
62%5%13%13%4
2388
November1st to 15thNight
53%5%13%16%9%2
2501
16th to endNight
62%5%10%15%5%
2730
December1st to 15thNight
73%48%11%2
2546
16th to endNight
74%48%8%3
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
25%30%25%13%33
60
16th to endDay
37%17%26%14%4
75
February1st to 15thDay
28%35%33%2
90
16th to endDay
38%19%24%15%2
195
March1st to 15thDay
28%20%22%21%6%
270
16th to endDay
28%16%31%13%7%2
288
April1st to 15thDay
32%17%27%12%8%1
270
16th to endDay
29%16%22%18%8%5%
270
May1st to 15thDay
31%11%26%17%9%3
288
16th to endDay
18%19%31%17%11%2
331
June1st to 15thDay
29%11%30%19%7%1
315
16th to endDay
20%13%32%21%10%1
315
July1st to 15thDay
16%6%32%24%15%4
305
16th to endDay
17%7%30%27%13%3
326
August1st to 15thDay
15%5%30%26%15%6%
313
16th to endDay
13%6%25%23%19%10%
332
September1st to 15thDay
20%7%25%16%17%12%
315
16th to endDay
16%7%25%22%18%10%
314
October1st to 15thDay
24%14%22%19%13%5%
315
16th to endDay
33%16%25%19%5%
315
November1st to 15thDay
22%13%31%18%11%1
247
16th to endDay
31%18%30%15%4
90
December1st to 15thDay
30%23%25%15%4
63
16th to endDay
43%35%17%3
64
January1st to 15thNight
32%18%28%16%4
720
16th to endNight
25%20%26%21%5%
768
February1st to 15thNight
26%21%30%19%1
704
16th to endNight
25%14%33%20%4
631
March1st to 15thNight
31%16%28%18%4
720
16th to endNight
26%14%26%22%8%1
768
April1st to 15thNight
29%14%30%22%3
718
16th to endNight
24%13%30%21%9%
687
May1st to 15thNight
28%5%24%31%9%
360
16th to endNight
16%10%32%32%7%
375
June1st to 15thNight
24%7%24%32%11%
360
16th to endNight
16%5%31%33%12%
360
July1st to 15thNight
11%429%36%16%1
340
16th to endNight
11%326%40%16%1
376
August1st to 15thNight
18%322%35%19%1
467
16th to endNight
13%225%35%21%2
726
September1st to 15thNight
19%421%32%19%2
720
16th to endNight
16%6%23%26%23%3
717
October1st to 15thNight
27%10%25%19%16%
720
16th to endNight
35%11%25%22%4
768
November1st to 15thNight
27%10%28%22%10%1
760
16th to endNight
33%15%24%17%8%
780
December1st to 15thNight
37%17%25%14%4
728
16th to endNight
37%13%29%15%21
768
Page generated at 2017-12-03 11:16:37. Version ac04

Copyright 2017 A. Danko


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