Bolingbroke
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bolingbroke 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
50%
15585
23%
47008
16%
15543
58%
15543
29%
28915

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
29%
720
24%
2327
10%
716
46%
716
22%
1429
January16th to endNight
29%
768
24%
2445
12%
768
44%
768
23%
1516
February1st to 15thNight
33%
703
26%
2110
12%
701
48%
701
27%
1287
February16th to endNight
29%
631
26%
1893
10%
631
44%
631
28%
1164
March1st to 15thNight
34%
720
26%
2043
12%
720
46%
720
30%
1237
March16th to endNight
42%
768
23%
2112
12%
768
50%
768
31%
1288
April1st to 15thNight
45%
679
25%
1937
17%
679
53%
679
34%
1137
April16th to endNight
52%
540
28%
1698
18%
540
62%
540
35%
933
May1st to 15thNight
55%
539
24%
1620
15%
539
62%
539
33%
960
May16th to endNight
64%
561
21%
1682
16%
561
67%
561
33%
1033
June1st to 15thNight
68%
540
17%
1620
14%
540
70%
540
30%
1022
June16th to endNight
74%
540
16%
1620
16%
540
74%
540
31%
1013
July1st to 15thNight
73%
510
11%
1530
9%
510
74%
510
27%
1018
July16th to endNight
75%
564
15%
1595
13%
531
76%
531
28%
1053
August1st to 15thNight
73%
539
16%
1636
16%
536
73%
536
27%
1091
August16th to endNight
64%
582
17%
1919
19%
582
65%
582
22%
1298
September1st to 15thNight
64%
720
18%
1980
17%
720
65%
720
27%
1330
September16th to endNight
60%
689
23%
1903
18%
689
64%
689
27%
1265
October1st to 15thNight
56%
660
31%
1829
25%
660
63%
660
36%
1105
October16th to endNight
54%
704
34%
2112
27%
704
64%
704
37%
1161
November1st to 15thNight
52%
700
31%
2221
25%
700
62%
700
36%
1200
November16th to endNight
44%
720
28%
2340
19%
720
57%
720
31%
1316
December1st to 15thNight
39%
720
25%
2340
18%
720
50%
720
26%
1414
December16th to endNight
36%
768
22%
2496
16%
768
45%
768
20%
1645

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
12%5%25%5%35%5%5%7%41%
47892
Night
11%42443445%7%46%
47209
TransparencyDay
39%6%11%18%17%6%
47593
Night
36%6%10%18%19%8%
47012
SeeingDay
14%6%18%22%23%13%
5460
Night
13%7%21%30%23%4
15589

By Month

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
16%6%24314445%46%
1611
16th to endDay
17%5%33413446%44%
1776
February1st to 15thDay
14%5%25%415%446%45%
1750
16th to endDay
16%5%2442335%6%44%
1580
March1st to 15thDay
14%5%24323447%47%
1917
16th to endDay
14%5%24424446%45%
2111
April1st to 15thDay
11%5%34423446%48%
2020
16th to endDay
9%413433447%51%
2262
May1st to 15thDay
10%4245%35%45%7%46%
2331
16th to endDay
9%415%5%46%6%6%9%40%
2431
June1st to 15thDay
9%5%26%6%47%6%7%10%33%
2340
16th to endDay
5%325%5%46%6%9%11%40%
2340
July1st to 15thDay
9%436%7%48%7%8%11%29%
2340
16th to endDay
5%436%7%5%9%9%10%11%26%
2465
August1st to 15thDay
9%6%26%6%5%7%7%9%10%28%
2310
16th to endDay
14%5%36%7%5%6%6%6%8%29%
2271
September1st to 15thDay
13%5%245%36%6%6%8%36%
1980
16th to endDay
16%426%6%34446%39%
1894
October1st to 15thDay
15%312313337%52%
1801
16th to endDay
11%31232334459%
1760
November1st to 15thDay
12%414312445%55%
1634
16th to endDay
14%5%23323445%50%
1620
December1st to 15thDay
15%5%24423446%45%
1620
16th to endDay
22%7%26%423336%37%
1728
January1st to 15thNight
16%5%24334435%47%
2327
16th to endNight
17%5%3442443445%
2445
February1st to 15thNight
14%425%324336%48%
2103
16th to endNight
14%41443345%6%47%
1893
March1st to 15thNight
11%424425%346%50%
2043
16th to endNight
13%41431335%8%49%
2112
April1st to 15thNight
12%31332445%7%50%
1937
16th to endNight
8%31342346%8%52%
1698
May1st to 15thNight
7%414425%46%9%49%
1619
16th to endNight
7%4245%36%6%6%8%45%
1682
June1st to 15thNight
7%4345%35%6%6%12%41%
1620
16th to endNight
4325%6%36%6%8%13%40%
1620
July1st to 15thNight
7%4245%47%9%8%13%34%
1620
16th to endNight
5%3245%48%7%9%13%35%
1703
August1st to 15thNight
6%425%6%5%6%7%7%12%36%
1647
16th to endNight
12%5%36%6%45%5%7%9%35%
1919
September1st to 15thNight
8%5%26%6%35%5%6%9%38%
1980
16th to endNight
12%5%25%5%345%5%7%42%
1903
October1st to 15thNight
13%5%23323436%52%
1829
16th to endNight
9%412323345%58%
2112
November1st to 15thNight
10%413313246%57%
2221
16th to endNight
13%413322435%54%
2340
December1st to 15thNight
13%6%23433446%46%
2340
16th to endNight
20%6%25%324346%39%
2496

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
39%47%15%26%6%
1612
16th to endDay
40%46%17%23%8%
1776
February1st to 15thDay
39%27%20%22%8%
1752
16th to endDay
39%46%19%22%7%
1580
March1st to 15thDay
37%5%9%18%20%9%
1917
16th to endDay
39%5%9%19%20%5%
2112
April1st to 15thDay
36%49%20%20%9%
2020
16th to endDay
31%411%20%23%7%
2262
May1st to 15thDay
35%6%12%20%21%4
2331
16th to endDay
37%7%13%24%14%2
2435
June1st to 15thDay
42%8%15%22%10%1
2340
16th to endDay
33%10%18%21%14%2
2340
July1st to 15thDay
43%11%20%15%6%2
2201
16th to endDay
43%11%18%19%6%1
2310
August1st to 15thDay
45%11%17%18%6%
2297
16th to endDay
50%10%13%14%10%1
2271
September1st to 15thDay
42%7%14%16%15%3
1980
16th to endDay
43%6%8%20%16%4
1894
October1st to 15thDay
33%310%21%23%8%
1801
16th to endDay
28%35%15%30%15%
1760
November1st to 15thDay
31%36%16%27%15%
1634
16th to endDay
37%36%15%25%10%
1620
December1st to 15thDay
39%410%18%19%8%
1620
16th to endDay
49%37%16%15%7%
1728
January1st to 15thNight
39%45%17%25%7%
2327
16th to endNight
41%35%15%23%11%
2445
February1st to 15thNight
37%3419%22%12%
2112
16th to endNight
38%36%18%23%10%
1893
March1st to 15thNight
34%49%19%21%9%
2043
16th to endNight
33%5%9%20%21%8%
2112
April1st to 15thNight
31%48%23%20%10%
1937
16th to endNight
29%5%11%21%21%11%
1698
May1st to 15thNight
31%7%12%19%23%5%
1620
16th to endNight
33%7%14%25%15%4
1684
June1st to 15thNight
34%8%17%25%12%
1620
16th to endNight
33%9%20%20%13%3
1620
July1st to 15thNight
35%12%24%18%6%2
1530
16th to endNight
34%12%23%18%8%1
1595
August1st to 15thNight
36%11%21%19%9%1
1636
16th to endNight
43%9%17%16%11%1
1919
September1st to 15thNight
38%10%14%16%16%3
1980
16th to endNight
40%7%10%19%16%5%
1903
October1st to 15thNight
33%48%18%22%11%
1829
16th to endNight
28%35%14%31%16%
2112
November1st to 15thNight
29%35%15%29%15%
2221
16th to endNight
33%36%16%26%13%
2340
December1st to 15thNight
38%38%19%21%8%
2340
16th to endNight
46%36%18%17%7%
2496

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
15%18%38%16%7%2
90
16th to endDay
14%32%38%7%7%
96
February1st to 15thDay
12%28%40%15%3
90
16th to endDay
20%19%45%11%2
81
March1st to 15thDay
18%14%31%23%11%1
207
16th to endDay
14%8%32%27%16%
288
April1st to 15thDay
17%14%23%19%21%3
270
16th to endDay
12%227%29%21%6%
270
May1st to 15thDay
12%12%23%20%15%14%
288
16th to endDay
13%218%23%26%15%
331
June1st to 15thDay
12%211%21%28%22%
315
16th to endDay
9%10%27%25%26%
315
July1st to 15thDay
8%8%18%33%30%
305
16th to endDay
46%18%39%30%
326
August1st to 15thDay
14%25%23%31%21%
313
16th to endDay
15%5%24%33%21%
332
September1st to 15thDay
16%110%21%32%17%
315
16th to endDay
20%113%28%23%12%
283
October1st to 15thDay
22%219%24%23%7%
255
16th to endDay
10%6%19%28%26%8%
272
November1st to 15thDay
26%7%27%18%17%2
142
16th to endDay
11%12%28%31%13%3
90
December1st to 15thDay
22%11%34%23%8%
90
16th to endDay
41%10%20%19%6%1
96
January1st to 15thNight
18%18%29%24%8%
720
16th to endNight
18%16%30%29%5%
768
February1st to 15thNight
16%14%30%31%6%
704
16th to endNight
16%15%35%29%3
631
March1st to 15thNight
13%13%35%28%8%
720
16th to endNight
15%11%25%31%14%
768
April1st to 15thNight
14%10%26%30%16%
679
16th to endNight
10%5%26%34%21%1
540
May1st to 15thNight
9%5%25%32%24%3
540
16th to endNight
10%115%35%30%6%
563
June1st to 15thNight
7%111%35%35%8%
540
16th to endNight
5%16%31%44%11%
540
July1st to 15thNight
8%6%26%41%15%
510
16th to endNight
6%16%26%46%12%
564
August1st to 15thNight
7%15%27%47%12%
539
16th to endNight
14%1425%42%12%
582
September1st to 15thNight
12%9%24%40%11%
720
16th to endNight
15%211%32%33%4
689
October1st to 15thNight
16%220%30%25%5%
660
16th to endNight
11%8%21%32%24%2
704
November1st to 15thNight
11%7%23%34%22%1
700
16th to endNight
14%11%25%31%15%1
720
December1st to 15thNight
16%10%27%29%13%1
720
16th to endNight
23%11%25%30%8%
768
Page generated at 2017-09-24 09:15:44. Version ac04

Copyright 2017 A. Danko


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