Bluewater Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bluewater Lake State Park clear sky chart from 2005-11-05 to 2017-09-23.

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
55%
15597
31%
47281
20%
15554
66%
15554
41%
24268

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
54%
720
32%
2327
25%
716
66%
716
43%
1099
January16th to endNight
50%
768
34%
2496
25%
768
64%
768
40%
1222
February1st to 15thNight
48%
700
30%
2288
23%
699
60%
699
41%
1113
February16th to endNight
38%
632
39%
1854
19%
632
60%
632
43%
913
March1st to 15thNight
50%
720
36%
1980
21%
720
62%
720
47%
1020
March16th to endNight
47%
768
35%
2112
16%
768
62%
768
51%
1047
April1st to 15thNight
37%
560
34%
1819
14%
560
61%
560
41%
836
April16th to endNight
36%
540
33%
1800
15%
540
60%
540
38%
837
May1st to 15thNight
45%
540
27%
1703
16%
539
59%
539
44%
829
May16th to endNight
48%
562
28%
1684
15%
561
62%
561
46%
822
June1st to 15thNight
56%
540
29%
1620
21%
540
63%
540
54%
744
June16th to endNight
67%
540
24%
1620
19%
540
72%
540
49%
793
July1st to 15thNight
65%
510
13%
1530
10%
510
67%
510
26%
976
July16th to endNight
70%
564
13%
1593
11%
531
71%
531
23%
1080
August1st to 15thNight
75%
539
16%
1626
16%
536
76%
536
28%
1011
August16th to endNight
75%
573
23%
1910
24%
573
76%
573
29%
1141
September1st to 15thNight
68%
540
25%
1800
27%
540
71%
540
27%
1113
September16th to endNight
70%
661
36%
1912
23%
661
80%
661
53%
938
October1st to 15thNight
59%
660
34%
1980
21%
660
70%
660
49%
979
October16th to endNight
64%
704
40%
2112
26%
704
75%
704
54%
985
November1st to 15thNight
62%
700
38%
2100
26%
700
72%
700
55%
957
November16th to endNight
56%
828
36%
2339
24%
828
66%
828
49%
1145
December1st to 15thNight
50%
900
31%
2520
17%
900
61%
900
45%
1280
December16th to endNight
39%
828
30%
2556
18%
828
53%
828
35%
1388

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
33245%35%45%6%56%
47618
Night
221332445%7%61%
47477
TransparencyDay
26%6%8%18%25%14%
47313
Night
21%6%10%21%26%14%
47283
SeeingDay
9%13%25%28%17%5%
5144
Night
410%24%33%23%3
15602

By Month

Percentage Cloud Cover SW (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
1214323436%65%
1611
16th to endDay
15%13323446%63%
1728
February1st to 15thDay
15%24423346%60%
1575
16th to endDay
3145%2436%9%58%
1615
March1st to 15thDay
1424425%45%7%58%
1980
16th to endDay
1324424447%60%
2112
April1st to 15thDay
12233245%5%7%61%
2129
16th to endDay
23145%23446%61%
2160
May1st to 15thDay
22244345%6%5%59%
2244
16th to endDay
33234245%45%61%
2429
June1st to 15thDay
211232435%6%66%
2340
16th to endDay
1113425%45%6%63%
2340
July1st to 15thDay
5%326%8%47%7%7%9%36%
2340
16th to endDay
5%6%37%9%5%9%8%7%10%26%
2467
August1st to 15thDay
7%6%37%9%5%7%7%7%7%31%
2325
16th to endDay
6%436%7%47%6%6%6%39%
2292
September1st to 15thDay
7%5%27%6%47%6%5%7%40%
2160
16th to endDay
331442434462%
1881
October1st to 15thDay
4214322435%65%
1650
16th to endDay
221232223472%
1760
November1st to 15thDay
1212313346%70%
1759
16th to endDay
1213323246%68%
1605
December1st to 15thDay
1312325%347%63%
1440
16th to endDay
15%2443345%8%56%
1676
January1st to 15thNight
212323346%67%
2327
16th to endNight
12123245%47%63%
2496
February1st to 15thNight
1313223346%65%
2277
16th to endNight
11221345%7%68%
1854
March1st to 15thNight
212313447%66%
1980
16th to endNight
1112223346%69%
2112
April1st to 15thNight
121232345%7%66%
1819
16th to endNight
1214323346%65%
1800
May1st to 15thNight
2213324446%63%
1703
16th to endNight
2213314346%67%
1684
June1st to 15thNight
213224345%69%
1620
16th to endNight
121242446%6%61%
1620
July1st to 15thNight
3425%6%37%7%8%11%38%
1620
16th to endNight
5%326%6%5%8%8%9%11%32%
1701
August1st to 15thNight
43145%46%6%8%11%42%
1635
16th to endNight
4425%5%26%6%7%10%44%
1910
September1st to 15thNight
5%426%5%45%5%7%9%42%
1800
16th to endNight
3212213336%68%
1912
October1st to 15thNight
3112224436%68%
1980
16th to endNight
121221333473%
2112
November1st to 15thNight
1222235%6%71%
2100
16th to endNight
1213213345%70%
2339
December1st to 15thNight
121232335%8%65%
2520
16th to endNight
242432445%8%58%
2556

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
20%5%10%26%30%7%
1612
16th to endDay
22%48%24%29%10%
1728
February1st to 15thDay
25%5%9%25%20%14%
1575
16th to endDay
22%5%6%23%31%9%
1615
March1st to 15thDay
24%5%5%22%30%11%
1980
16th to endDay
23%36%20%31%13%
2112
April1st to 15thDay
21%46%21%32%13%
2129
16th to endDay
24%37%18%31%15%
2160
May1st to 15thDay
23%6%6%16%31%15%
2244
16th to endDay
23%5%7%12%32%17%
2432
June1st to 15thDay
17%45%10%28%33%
2340
16th to endDay
20%46%11%23%33%
2340
July1st to 15thDay
39%9%11%15%9%13%
2201
16th to endDay
47%13%15%15%6%1
2312
August1st to 15thDay
46%10%12%12%12%5%
2310
16th to endDay
40%9%11%16%17%5%
2292
September1st to 15thDay
40%8%11%15%15%9%
2160
16th to endDay
23%46%15%27%21%
1881
October1st to 15thDay
23%45%16%33%16%
1650
16th to endDay
16%46%14%40%16%
1760
November1st to 15thDay
16%37%25%31%16%
1759
16th to endDay
19%36%19%34%16%
1605
December1st to 15thDay
20%6%11%32%21%7%
1440
16th to endDay
26%6%13%28%20%3
1676
January1st to 15thNight
18%5%9%24%33%8%
2327
16th to endNight
19%6%9%22%31%10%
2496
February1st to 15thNight
20%410%25%24%14%
2288
16th to endNight
15%7%7%24%35%9%
1854
March1st to 15thNight
18%46%25%33%11%
1980
16th to endNight
16%37%22%37%12%
2112
April1st to 15thNight
17%46%25%31%14%
1819
16th to endNight
20%37%19%31%18%
1800
May1st to 15thNight
20%410%18%30%16%
1704
16th to endNight
18%48%15%31%20%
1685
June1st to 15thNight
16%35%12%25%37%
1620
16th to endNight
19%49%12%17%35%
1620
July1st to 15thNight
36%11%14%14%10%13%
1530
16th to endNight
37%14%21%16%7%1
1593
August1st to 15thNight
31%12%19%14%13%7%
1626
16th to endNight
32%9%16%20%13%7%
1910
September1st to 15thNight
36%8%13%16%13%12%
1800
16th to endNight
17%47%19%26%24%
1912
October1st to 15thNight
18%47%18%30%20%
1980
16th to endNight
15%35%18%36%19%
2112
November1st to 15thNight
14%47%26%34%14%
2100
16th to endNight
17%37%19%33%18%
2339
December1st to 15thNight
18%5%12%30%24%8%
2520
16th to endNight
24%7%13%26%23%5%
2556

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
6%26%35%21%8%1
90
16th to endDay
9%17%37%13%16%5%
96
February1st to 15thDay
7%17%23%26%18%5%
90
16th to endDay
8%32%24%17%16%1
129
March1st to 15thDay
11%22%28%22%13%1
270
16th to endDay
12%22%36%20%6%
288
April1st to 15thDay
9%29%27%22%7%2
269
16th to endDay
15%30%30%17%41
270
May1st to 15thDay
7%20%39%23%7%1
288
16th to endDay
7%18%34%26%10%2
330
June1st to 15thDay
5%11%32%31%15%3
315
16th to endDay
4419%42%21%7%
315
July1st to 15thDay
8%13%41%29%6%
305
16th to endDay
11%17%28%33%18%
327
August1st to 15thDay
12%10%33%30%12%
315
16th to endDay
9%117%32%28%10%
332
September1st to 15thDay
11%220%37%22%5%
315
16th to endDay
9%9%28%29%18%4
248
October1st to 15thDay
28%30%27%22%8%
90
16th to endDay
7%5%26%32%25%4
96
November1st to 15thDay
316%18%40%16%4
90
16th to endDay
7%25%33%20%12%1
90
December1st to 15thDay
30%27%27%14%
90
16th to endDay
7%23%28%29%8%3
96
January1st to 15thNight
215%23%34%19%5%
720
16th to endNight
314%28%32%16%4
768
February1st to 15thNight
314%29%33%15%2
704
16th to endNight
122%36%29%9%
632
March1st to 15thNight
317%25%34%17%1
720
16th to endNight
213%34%33%15%
768
April1st to 15thNight
222%34%30%9%
560
16th to endNight
420%34%29%10%1
540
May1st to 15thNight
48%37%36%12%
540
16th to endNight
38%34%33%18%2
563
June1st to 15thNight
15%32%42%16%1
540
16th to endNight
2121%42%30%1
540
July1st to 15thNight
6%110%36%40%4
510
16th to endNight
6%17%23%50%11%
564
August1st to 15thNight
7%5%31%43%11%
539
16th to endNight
5%7%31%47%7%
573
September1st to 15thNight
7%110%38%36%5%
540
16th to endNight
4317%34%32%8%
661
October1st to 15thNight
46%26%38%20%4
660
16th to endNight
26%22%34%26%6%
704
November1st to 15thNight
28%24%32%27%4
700
16th to endNight
414%21%29%24%5%
828
December1st to 15thNight
5%15%26%34%16%2
900
16th to endNight
417%33%27%14%2
828
Page generated at 2017-09-24 07:15:49. Version ac04

Copyright 2017 A. Danko


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