Bootland Farm
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bootland Farm clear sky chart from 2005-11-05 to 2017-08-12.

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
25%
14516
11%
46505
7%
14485
31%
14485
16%
33252

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
5%
2506
2%
716
18%
716
6%
2054
January16th to endNight
19%
768
10%
2619
5%
768
26%
768
11%
1977
February1st to 15thNight
16%
703
9%
2287
3%
701
23%
701
10%
1765
February16th to endNight
19%
631
12%
1970
5%
631
28%
631
13%
1444
March1st to 15thNight
13%
720
9%
2076
5%
720
18%
720
14%
1567
March16th to endNight
20%
768
13%
2051
6%
768
27%
768
22%
1406
April1st to 15thNight
21%
718
14%
1796
5%
718
26%
718
19%
1322
April16th to endNight
28%
639
16%
1719
7%
639
35%
639
21%
1209
May1st to 15thNight
24%
360
12%
1440
11%
360
32%
360
16%
951
May16th to endNight
29%
375
11%
1497
8%
374
41%
374
19%
937
June1st to 15thNight
30%
360
8%
1440
7%
360
39%
360
15%
950
June16th to endNight
39%
360
7%
1440
9%
360
43%
360
19%
909
July1st to 15thNight
50%
340
15%
1360
20%
340
57%
340
28%
756
July16th to endNight
57%
376
14%
1418
15%
354
63%
354
27%
808
August1st to 15thNight
37%
457
12%
1506
10%
455
41%
455
26%
933
August16th to endNight
33%
632
13%
1682
6%
632
37%
632
36%
1041
September1st to 15thNight
41%
660
14%
1650
7%
660
44%
660
28%
1150
September16th to endNight
44%
657
19%
1803
13%
657
48%
657
30%
1167
October1st to 15thNight
31%
660
16%
1980
11%
660
39%
660
19%
1382
October16th to endNight
22%
704
10%
2182
5%
704
29%
704
12%
1669
November1st to 15thNight
21%
700
13%
2355
9%
700
28%
700
15%
1676
November16th to endNight
16%
720
7%
2520
5%
720
20%
720
9%
1943
December1st to 15thNight
14%
720
5%
2520
3%
720
18%
720
7%
2047
December16th to endNight
12%
768
7%
2688
3%
768
18%
768
8%
2189

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%8%36%5%3445%6%32%
47479
Night
17%9%46%6%34445%32%
46675
Cloud CoverDay
31%6%25%423345%29%
47489
Night
30%7%25%42333431%
46680
TransparencyDay
51%6%11%19%9%1
47167
Night
52%5%11%19%9%
46505
SeeingDay
22%13%29%21%9%3
5292
Night
22%12%29%24%9%
14517

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%14%6%8%7%23445%21%
1432
16th to endDay
14%15%5%8%9%35%445%22%
1603
February1st to 15thDay
12%13%7%13%7%35%44422%
1575
16th to endDay
17%12%5%7%7%45%34425%
1503
March1st to 15thDay
17%11%48%8%35%44426%
1872
16th to endDay
14%8%35%5%34345%40%
2172
April1st to 15thDay
23%10%36%42334434%
2152
16th to endDay
21%8%25%414345%36%
2250
May1st to 15thDay
20%8%36%5%23446%33%
2511
16th to endDay
17%6%35%5%35%45%6%36%
2618
June1st to 15thDay
21%7%35%5%35%35%6%31%
2520
16th to endDay
17%5%25%5%36%5%6%7%33%
2520
July1st to 15thDay
11%6%245%36%5%7%9%37%
2520
16th to endDay
11%426%5%35%5%7%10%36%
2654
August1st to 15thDay
11%6%26%6%345%6%7%37%
2357
16th to endDay
12%5%25%6%345%5%8%39%
2157
September1st to 15thDay
17%5%25%5%33347%40%
1980
16th to endDay
15%5%2442335%6%44%
1827
October1st to 15thDay
22%8%36%5%34445%32%
1650
16th to endDay
26%9%47%5%34345%24%
1689
November1st to 15thDay
15%9%46%4245%46%35%
1501
16th to endDay
22%12%5%7%6%345%35%23%
1440
December1st to 15thDay
20%17%5%10%7%35%44415%
1440
16th to endDay
22%16%6%8%6%24235%20%
1536
January1st to 15thNight
16%15%7%10%7%46%44418%
2506
16th to endNight
13%15%5%9%7%35%435%26%
2619
February1st to 15thNight
13%14%6%9%8%35%446%23%
2285
16th to endNight
16%10%48%8%35%35%5%28%
1970
March1st to 15thNight
17%13%5%7%6%3433430%
2064
16th to endNight
15%6%36%5%33346%40%
2051
April1st to 15thNight
23%8%36%5%24435%34%
1796
16th to endNight
19%9%25%5%34335%37%
1719
May1st to 15thNight
22%7%245%24335%37%
1440
16th to endNight
16%5%245%25%5%47%39%
1495
June1st to 15thNight
17%6%35%6%25%45%6%35%
1440
16th to endNight
15%5%15%5%25%5%7%7%38%
1440
July1st to 15thNight
9%5%24424448%47%
1440
16th to endNight
10%3245%345%6%9%45%
1514
August1st to 15thNight
9%425%6%335%5%9%43%
1516
16th to endNight
9%415%42435%7%50%
1682
September1st to 15thNight
16%5%25%5%24346%41%
1650
16th to endNight
16%4245%23335%48%
1803
October1st to 15thNight
21%7%35%424446%35%
1980
16th to endNight
23%10%36%5%345%46%26%
2182
November1st to 15thNight
19%9%35%5%34445%32%
2355
16th to endNight
21%13%5%9%6%33435%24%
2520
December1st to 15thNight
21%16%6%8%7%3444419%
2520
16th to endNight
24%15%6%8%6%3434320%
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
24%13%6%6%7%2344423%
1432
16th to endDay
17%13%5%8%8%3444424%
1603
February1st to 15thDay
19%11%5%11%6%3423426%
1575
16th to endDay
23%11%5%7%6%3333328%
1503
March1st to 15thDay
45%5%15%42323322%
1883
16th to endDay
43%41231222330%
2171
April1st to 15thDay
34%7%2431223335%
2152
16th to endDay
31%6%1331334436%
2250
May1st to 15thDay
46%5%2431223325%
2511
16th to endDay
44%31321223428%
2618
June1st to 15thDay
38%435%423335%26%
2520
16th to endDay
37%314334445%27%
2520
July1st to 15thDay
12%424425%6%6%8%40%
2520
16th to endDay
11%425%5%36%5%7%9%39%
2654
August1st to 15thDay
41%314433345%24%
2357
16th to endDay
45%31332223426%
2157
September1st to 15thDay
23%415%5%23346%39%
1980
16th to endDay
22%414423346%42%
1827
October1st to 15thDay
25%6%25%434336%33%
1650
16th to endDay
30%7%36%5%2334328%
1689
November1st to 15thDay
33%7%2431243431%
1501
16th to endDay
37%8%46%5%2333321%
1440
December1st to 15thDay
27%13%5%7%5%33335%19%
1440
16th to endDay
27%15%48%42332424%
1536
January1st to 15thNight
24%12%5%8%7%35%33322%
2506
16th to endNight
20%13%5%7%6%3433329%
2619
February1st to 15thNight
22%12%48%6%33335%26%
2278
16th to endNight
25%9%27%5%2434430%
1970
March1st to 15thNight
46%6%2432112324%
2076
16th to endNight
44%32431122331%
2051
April1st to 15thNight
31%5%1441222438%
1796
16th to endNight
25%7%24423235%39%
1719
May1st to 15thNight
42%5%1231222332%
1440
16th to endNight
37%31222243435%
1495
June1st to 15thNight
31%5%245%24435%31%
1440
16th to endNight
29%41433345%6%31%
1440
July1st to 15thNight
9%334425%45%8%49%
1440
16th to endNight
10%3144345%6%8%48%
1514
August1st to 15thNight
39%23422346%30%
1516
16th to endNight
41%2331222434%
1682
September1st to 15thNight
21%5%25%423335%42%
1650
16th to endNight
23%41432222447%
1803
October1st to 15thNight
26%6%34323335%36%
1980
16th to endNight
28%8%35%5%24335%28%
2182
November1st to 15thNight
40%7%1431332328%
2355
16th to endNight
42%9%35%31222322%
2520
December1st to 15thNight
32%12%36%43333323%
2520
16th to endNight
33%12%46%42223223%
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
65%5%9%12%5%1
1433
16th to endDay
63%5%10%12%7%
1603
February1st to 15thDay
64%411%14%4
1577
16th to endDay
60%410%13%9%1
1503
March1st to 15thDay
60%5%10%15%7%
1883
16th to endDay
45%48%19%15%5%
2172
April1st to 15thDay
54%37%18%13%2
2152
16th to endDay
48%47%18%16%3
2250
May1st to 15thDay
51%5%8%17%14%2
2511
16th to endDay
47%6%12%19%12%2
2622
June1st to 15thDay
52%6%10%20%9%
2520
16th to endDay
47%7%13%19%11%1
2520
July1st to 15thDay
38%7%14%27%12%
2371
16th to endDay
41%9%16%23%9%
2487
August1st to 15thDay
43%8%14%21%10%
2343
16th to endDay
40%7%15%25%10%
2157
September1st to 15thDay
43%5%13%26%10%
1980
16th to endDay
39%7%13%30%9%
1827
October1st to 15thDay
52%6%10%20%9%
1650
16th to endDay
62%6%11%14%5%
1689
November1st to 15thDay
48%7%15%20%7%
1501
16th to endDay
62%6%11%12%5%1
1440
December1st to 15thDay
70%6%11%9%2
1440
16th to endDay
66%5%11%10%5%
1536
January1st to 15thNight
68%6%9%9%4
2506
16th to endNight
60%5%10%16%7%
2619
February1st to 15thNight
61%5%11%15%5%
2287
16th to endNight
56%412%17%9%
1970
March1st to 15thNight
58%411%18%7%
2076
16th to endNight
45%410%20%16%3
2051
April1st to 15thNight
52%48%18%14%1
1796
16th to endNight
48%47%19%17%3
1719
May1st to 15thNight
49%47%19%14%4
1440
16th to endNight
42%7%13%20%13%2
1497
June1st to 15thNight
47%7%11%22%9%1
1440
16th to endNight
42%7%15%19%14%
1440
July1st to 15thNight
33%6%13%29%15%1
1360
16th to endNight
33%7%16%27%14%
1418
August1st to 15thNight
35%9%17%24%12%
1506
16th to endNight
32%6%16%32%11%
1682
September1st to 15thNight
43%6%12%27%10%
1650
16th to endNight
39%412%34%9%
1803
October1st to 15thNight
49%5%10%21%12%
1980
16th to endNight
58%6%13%15%6%
2182
November1st to 15thNight
52%6%12%17%10%
2355
16th to endNight
62%5%12%15%3
2520
December1st to 15thNight
67%5%12%11%2
2520
16th to endNight
68%5%9%11%5%
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
28%26%18%23%3
60
16th to endDay
37%10%37%9%5%
75
February1st to 15thDay
30%24%35%8%1
90
16th to endDay
32%22%26%14%4
162
March1st to 15thDay
25%18%33%18%4
270
16th to endDay
22%18%29%18%8%1
288
April1st to 15thDay
27%23%26%14%6%
270
16th to endDay
24%17%27%17%8%4
270
May1st to 15thDay
30%11%28%17%8%3
288
16th to endDay
24%14%30%20%8%2
331
June1st to 15thDay
27%11%29%21%7%1
315
16th to endDay
15%11%35%24%11%1
315
July1st to 15thDay
13%6%32%28%13%5%
305
16th to endDay
11%6%32%30%15%4
326
August1st to 15thDay
12%6%25%34%11%9%
297
16th to endDay
14%426%29%14%9%
268
September1st to 15thDay
18%6%25%18%18%12%
255
16th to endDay
16%10%27%20%16%7%
254
October1st to 15thDay
23%11%29%21%11%2
255
16th to endDay
29%19%29%14%6%
259
November1st to 15thDay
21%12%30%23%9%1
155
16th to endDay
35%16%31%10%6%
60
December1st to 15thDay
18%25%38%15%3
60
16th to endDay
42%21%32%3
64
January1st to 15thNight
24%19%34%17%4
720
16th to endNight
21%15%34%23%4
768
February1st to 15thNight
19%16%37%21%4
704
16th to endNight
22%17%33%20%5%
631
March1st to 15thNight
25%16%32%22%2
720
16th to endNight
19%16%28%24%10%
768
April1st to 15thNight
27%16%29%21%5%
718
16th to endNight
25%14%27%24%8%
639
May1st to 15thNight
26%7%27%27%9%1
360
16th to endNight
18%6%37%26%11%
375
June1st to 15thNight
18%8%31%32%8%
360
16th to endNight
17%6%25%36%12%
360
July1st to 15thNight
9%428%39%17%1
340
16th to endNight
9%224%44%15%2
376
August1st to 15thNight
12%5%22%37%19%2
457
16th to endNight
11%327%36%18%1
632
September1st to 15thNight
19%6%25%27%18%2
660
16th to endNight
18%8%23%27%20%1
657
October1st to 15thNight
25%10%26%24%11%1
660
16th to endNight
28%15%26%22%6%
704
November1st to 15thNight
24%11%31%21%10%
700
16th to endNight
30%18%25%18%6%
720
December1st to 15thNight
29%16%32%17%3
720
16th to endNight
33%13%32%16%3
768
Page generated at 2017-08-13 14:16:38. Version ac04

Copyright 2017 A. Danko


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