Blueberry Pond Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Blueberry Pond Observatory clear sky chart from 2005-11-05 to 2017-09-21.

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
31%
14825
17%
47028
8%
14793
42%
14793
21%
30933

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
20%
720
19%
2506
6%
716
36%
716
18%
1576
January16th to endNight
14%
768
19%
2688
4%
768
33%
768
15%
1730
February1st to 15thNight
18%
704
15%
2246
5%
701
30%
701
15%
1547
February16th to endNight
23%
631
20%
1893
7%
631
39%
631
19%
1277
March1st to 15thNight
19%
720
17%
2127
5%
720
32%
720
18%
1481
March16th to endNight
26%
768
21%
2074
8%
768
37%
768
23%
1368
April1st to 15thNight
26%
717
19%
1795
5%
717
34%
717
23%
1273
April16th to endNight
30%
540
17%
1620
6%
540
38%
540
21%
1101
May1st to 15thNight
31%
540
14%
1620
8%
540
38%
540
19%
1126
May16th to endNight
32%
421
11%
1543
10%
420
37%
420
13%
1113
June1st to 15thNight
38%
360
9%
1440
9%
360
45%
360
13%
1011
June16th to endNight
50%
360
9%
1440
13%
360
54%
360
20%
910
July1st to 15thNight
54%
340
10%
1360
16%
340
57%
340
21%
847
July16th to endNight
56%
376
13%
1418
17%
354
59%
354
20%
874
August1st to 15thNight
55%
517
14%
1588
10%
515
58%
515
26%
1020
August16th to endNight
57%
642
22%
1788
14%
642
60%
642
33%
1117
September1st to 15thNight
46%
720
19%
1887
10%
720
51%
720
34%
1220
September16th to endNight
47%
681
25%
1880
15%
681
55%
681
35%
1120
October1st to 15thNight
37%
660
22%
1862
11%
660
47%
660
26%
1223
October16th to endNight
28%
704
17%
2278
8%
704
39%
704
20%
1494
November1st to 15thNight
32%
700
22%
2277
11%
700
46%
700
23%
1437
November16th to endNight
27%
720
20%
2340
8%
720
40%
720
19%
1508
December1st to 15thNight
19%
747
17%
2661
4%
747
35%
747
16%
1772
December16th to endNight
18%
769
18%
2697
5%
769
33%
769
16%
1788

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%6%2442445%7%38%
47826
Night
18%7%24424446%39%
47198
Cloud CoverDay
18%6%25%42445%7%38%
47836
Night
18%7%24424446%39%
47203
TransparencyDay
44%411%22%14%1
47514
Night
45%411%23%14%1
47028
SeeingDay
22%9%30%22%10%3
5905
Night
22%9%29%27%10%1
14825

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%5%26%425%446%40%
1432
16th to endDay
16%8%25%32435%6%40%
1536
February1st to 15thDay
17%8%25%5%445%5%5%34%
1612
16th to endDay
14%10%36%5%35%446%35%
1580
March1st to 15thDay
20%9%345%33346%36%
1823
16th to endDay
15%7%45%5%23335%42%
2148
April1st to 15thDay
19%6%25%4245%46%38%
2152
16th to endDay
20%5%135%2445%5%40%
2340
May1st to 15thDay
25%7%36%423446%31%
2332
16th to endDay
21%6%245%3445%8%33%
2582
June1st to 15thDay
25%7%245%23447%31%
2520
16th to endDay
19%5%25%5%35%5%48%34%
2520
July1st to 15thDay
13%5%345%36%5%6%9%36%
2520
16th to endDay
14%5%145%36%6%7%8%36%
2654
August1st to 15thDay
14%5%245%25%5%6%9%37%
2349
16th to endDay
12%3144245%6%8%46%
2411
September1st to 15thDay
14%5%14423447%47%
2072
16th to endDay
14%5%13312346%52%
1873
October1st to 15thDay
19%7%25%433335%41%
1767
16th to endDay
19%6%25%424336%41%
1592
November1st to 15thDay
20%6%2331335%6%41%
1581
16th to endDay
22%6%1441233443%
1620
December1st to 15thDay
23%7%25%333445%37%
1290
16th to endDay
23%10%34333335%34%
1520
January1st to 15thNight
15%8%2443435%6%40%
2506
16th to endNight
16%9%36%424345%39%
2688
February1st to 15thNight
14%8%35%7%45%446%34%
2245
16th to endNight
16%10%345%33345%39%
1893
March1st to 15thNight
19%10%26%43345%6%34%
2114
16th to endNight
17%5%25%32345%5%43%
2074
April1st to 15thNight
20%7%24424446%37%
1795
16th to endNight
21%5%345%25%435%37%
1620
May1st to 15thNight
20%7%35%5%25%45%7%32%
1620
16th to endNight
21%8%47%435%45%7%27%
1541
June1st to 15thNight
25%7%25%5%24447%29%
1440
16th to endNight
20%5%3342445%7%37%
1440
July1st to 15thNight
14%5%25%6%35%5%5%9%36%
1440
16th to endNight
14%6%15%426%5%7%9%36%
1514
August1st to 15thNight
12%5%245%345%6%9%38%
1598
16th to endNight
13%41442445%8%46%
1788
September1st to 15thNight
14%5%24323345%48%
1887
16th to endNight
13%5%13312436%53%
1880
October1st to 15thNight
19%5%24424345%42%
1862
16th to endNight
22%5%24424346%39%
2278
November1st to 15thNight
19%5%2432445%6%42%
2277
16th to endNight
18%5%24424435%42%
2340
December1st to 15thNight
21%9%2442334438%
2661
16th to endNight
22%9%24423445%37%
2697

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%6%26%334446%40%
1432
16th to endDay
16%7%25%42445%6%40%
1536
February1st to 15thDay
17%8%25%5%35%45%5%34%
1612
16th to endDay
14%10%45%6%245%46%36%
1580
March1st to 15thDay
20%8%25%5%24337%35%
1833
16th to endDay
15%7%36%423345%42%
2148
April1st to 15thDay
18%6%25%5%24446%38%
2152
16th to endDay
19%6%145%2445%6%40%
2340
May1st to 15thDay
24%6%36%5%23446%31%
2332
16th to endDay
21%5%25%5%3445%8%33%
2582
June1st to 15thDay
25%6%25%42435%7%32%
2520
16th to endDay
19%5%25%5%345%47%34%
2520
July1st to 15thDay
12%5%35%436%6%6%9%35%
2520
16th to endDay
13%4245%36%6%6%9%37%
2654
August1st to 15thDay
13%5%25%435%5%7%9%38%
2349
16th to endDay
11%4134245%6%8%46%
2411
September1st to 15thDay
14%414323448%47%
2072
16th to endDay
13%5%13422346%51%
1873
October1st to 15thDay
18%6%35%433235%41%
1767
16th to endDay
19%6%24424436%41%
1592
November1st to 15thDay
20%5%23313446%42%
1581
16th to endDay
22%6%2342233443%
1620
December1st to 15thDay
22%7%34323435%38%
1290
16th to endDay
23%10%24423345%34%
1520
January1st to 15thNight
15%8%3442445%6%40%
2506
16th to endNight
16%9%36%423445%39%
2688
February1st to 15thNight
14%8%35%7%45%45%6%34%
2238
16th to endNight
16%9%345%33345%39%
1893
March1st to 15thNight
20%9%35%5%2345%6%34%
2127
16th to endNight
17%5%25%423445%43%
2073
April1st to 15thNight
20%7%24425%445%37%
1795
16th to endNight
22%5%345%25%446%37%
1620
May1st to 15thNight
20%7%35%425%45%8%31%
1620
16th to endNight
22%8%46%5%35%447%27%
1541
June1st to 15thNight
25%7%25%4245%37%29%
1440
16th to endNight
21%5%14424448%36%
1440
July1st to 15thNight
14%5%25%5%45%5%6%8%36%
1440
16th to endNight
14%5%245%346%7%9%35%
1514
August1st to 15thNight
13%6%245%435%6%8%38%
1598
16th to endNight
13%31443346%7%46%
1788
September1st to 15thNight
13%6%23423345%48%
1887
16th to endNight
13%5%13322436%53%
1880
October1st to 15thNight
19%5%24424446%41%
1862
16th to endNight
22%5%24424345%39%
2278
November1st to 15thNight
18%5%2432345%5%43%
2277
16th to endNight
18%6%25%424435%42%
2340
December1st to 15thNight
21%10%24323345%38%
2661
16th to endNight
22%9%2442343437%
2697

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
44%410%24%14%2
1433
16th to endDay
43%312%25%13%1
1536
February1st to 15thDay
49%412%20%12%1
1615
16th to endDay
48%210%21%13%3
1580
March1st to 15thDay
49%311%19%12%3
1833
16th to endDay
43%37%20%18%5%
2148
April1st to 15thDay
45%47%21%16%4
2152
16th to endDay
44%410%22%15%3
2340
May1st to 15thDay
52%48%16%15%2
2332
16th to endDay
48%6%12%19%11%1
2586
June1st to 15thDay
51%413%20%9%
2520
16th to endDay
48%5%11%22%11%1
2520
July1st to 15thDay
40%7%13%25%12%
2371
16th to endDay
39%7%15%23%12%1
2487
August1st to 15thDay
39%6%18%25%10%
2335
16th to endDay
33%415%27%17%1
2411
September1st to 15thDay
35%5%11%27%19%1
2072
16th to endDay
33%5%8%28%21%2
1873
October1st to 15thDay
45%28%25%14%2
1767
16th to endDay
44%312%24%14%1
1592
November1st to 15thDay
41%413%24%14%1
1581
16th to endDay
44%313%19%16%1
1620
December1st to 15thDay
48%413%20%13%
1290
16th to endDay
52%310%20%12%1
1520
January1st to 15thNight
43%412%24%13%1
2506
16th to endNight
46%39%22%14%2
2688
February1st to 15thNight
50%311%20%12%1
2246
16th to endNight
47%410%22%13%2
1893
March1st to 15thNight
50%38%21%13%2
2127
16th to endNight
42%39%19%19%5%
2074
April1st to 15thNight
48%36%21%17%2
1795
16th to endNight
48%310%19%13%4
1620
May1st to 15thNight
49%5%10%18%14%2
1620
16th to endNight
56%5%10%16%10%1
1543
June1st to 15thNight
54%6%9%19%8%1
1440
16th to endNight
44%5%13%22%12%
1440
July1st to 15thNight
42%6%15%23%11%
1360
16th to endNight
41%7%15%23%10%
1418
August1st to 15thNight
39%7%15%25%10%
1588
16th to endNight
35%5%11%29%17%
1788
September1st to 15thNight
37%49%30%15%1
1887
16th to endNight
33%39%31%20%1
1880
October1st to 15thNight
43%39%25%15%1
1862
16th to endNight
46%311%25%12%1
2278
November1st to 15thNight
41%412%23%15%1
2277
16th to endNight
44%412%21%15%1
2340
December1st to 15thNight
49%310%23%12%
2661
16th to endNight
50%212%21%12%
2697

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
18%18%33%23%6%
60
16th to endDay
21%18%34%20%4
64
February1st to 15thDay
26%10%39%19%3
226
16th to endDay
20%12%39%21%5%
239
March1st to 15thDay
28%15%35%15%4
270
16th to endDay
20%17%35%16%6%3
288
April1st to 15thDay
27%9%34%18%7%2
270
16th to endDay
23%12%34%17%7%4
270
May1st to 15thDay
34%7%29%16%9%3
288
16th to endDay
24%7%35%23%8%
331
June1st to 15thDay
24%9%34%21%7%2
315
16th to endDay
20%8%33%25%10%2
315
July1st to 15thDay
16%431%27%14%6%
305
16th to endDay
12%429%32%16%4
326
August1st to 15thDay
15%6%23%30%20%3
313
16th to endDay
14%6%20%27%18%12%
332
September1st to 15thDay
16%5%27%24%17%7%
315
16th to endDay
18%6%29%20%12%13%
275
October1st to 15thDay
21%11%19%25%15%6%
246
16th to endDay
26%10%32%21%10%
240
November1st to 15thDay
26%12%25%22%9%2
235
16th to endDay
27%12%27%21%8%1
240
December1st to 15thDay
24%12%34%20%7%
78
16th to endDay
34%18%28%17%1
64
January1st to 15thNight
20%17%37%19%5%
720
16th to endNight
22%18%35%20%2
768
February1st to 15thNight
20%15%38%21%3
704
16th to endNight
22%12%35%24%5%
631
March1st to 15thNight
25%14%35%20%3
720
16th to endNight
22%12%33%24%7%1
768
April1st to 15thNight
24%10%34%25%5%
717
16th to endNight
24%9%29%27%8%
540
May1st to 15thNight
25%7%29%26%9%1
540
16th to endNight
27%6%23%29%11%1
421
June1st to 15thNight
29%5%18%33%13%1
360
16th to endNight
21%316%41%15%
360
July1st to 15thNight
17%215%41%20%2
340
16th to endNight
17%114%40%24%1
376
August1st to 15thNight
14%315%41%21%2
517
16th to endNight
15%216%39%22%4
642
September1st to 15thNight
17%224%33%19%3
720
16th to endNight
17%5%23%28%21%3
681
October1st to 15thNight
22%6%24%27%16%2
660
16th to endNight
24%11%30%25%7%
704
November1st to 15thNight
23%8%31%26%8%2
700
16th to endNight
22%12%30%23%9%
720
December1st to 15thNight
27%12%34%19%4
747
16th to endNight
27%14%35%18%3
769
Page generated at 2017-09-22 07:35:36. Version ac04

Copyright 2017 A. Danko


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