Hay House Farm Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hay House Farm Observatory clear sky chart from 2005-11-06 to 2024-03-01.

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
40%
23875
22%
80012
13%
23776
50%
23776
25%
48806

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 10thNight
22%
753
28%
3996
8%
737
42%
737
16%
2103
January11th to 20thNight
25%
760
28%
3938
10%
740
43%
740
14%
2195
January21st to endNight
22%
831
17%
4436
10%
814
43%
814
15%
2660
February1st to 10thNight
27%
760
21%
2470
11%
760
41%
760
24%
1527
February11th to 20thNight
16%
740
21%
2386
7%
740
34%
740
19%
1502
February21st to endNight
20%
628
25%
1837
9%
628
38%
628
22%
1189
March1st to 10thNight
26%
723
27%
1987
11%
723
42%
723
29%
1226
March11th to 20thNight
24%
720
21%
1980
9%
720
35%
720
25%
1296
March21st to endNight
27%
792
21%
2178
9%
792
37%
792
25%
1422
April1st to 10thNight
26%
720
22%
1815
5%
720
37%
720
29%
1179
April11th to 20thNight
33%
711
23%
1775
7%
711
41%
711
35%
1107
April21st to endNight
36%
720
22%
1800
9%
720
43%
720
33%
1171
May1st to 10thNight
36%
561
18%
1641
8%
561
43%
561
25%
1072
May11th to 20thNight
43%
531
15%
1592
8%
531
48%
531
25%
1062
May21st to endNight
55%
414
16%
1576
16%
414
59%
414
23%
965
June1st to 10thNight
61%
360
20%
1440
22%
360
66%
360
27%
799
June11th to 20thNight
60%
360
15%
1440
16%
360
63%
360
23%
850
June21st to endNight
61%
360
20%
1440
20%
360
67%
360
27%
816
July1st to 10thNight
59%
412
16%
1462
17%
412
61%
412
25%
895
July11th to 20thNight
72%
522
15%
1566
12%
522
74%
522
33%
939
July21st to endNight
65%
591
17%
1672
14%
558
67%
558
30%
1059
August1st to 10thNight
65%
537
16%
1600
13%
534
66%
534
28%
1041
August11th to 20thNight
59%
579
17%
1643
12%
579
61%
579
26%
1108
August21st to endNight
60%
792
17%
1980
11%
792
61%
792
31%
1363
September1st to 10thNight
60%
720
22%
1800
14%
720
62%
720
32%
1205
September11th to 20thNight
59%
720
28%
1838
21%
720
62%
720
35%
1174
September21st to endNight
45%
720
20%
2059
16%
720
51%
720
24%
1375
October1st to 10thNight
51%
720
22%
2160
21%
720
57%
720
30%
1349
October11th to 20thNight
42%
720
27%
2160
20%
720
54%
720
29%
1320
October21st to endNight
41%
792
29%
2376
20%
792
55%
792
32%
1398
November1st to 10thNight
42%
740
29%
2221
19%
740
54%
740
32%
1321
November11th to 20thNight
34%
760
26%
2490
15%
760
49%
760
28%
1431
November21st to endNight
38%
760
25%
2660
17%
760
52%
760
28%
1500
December1st to 10thNight
28%
760
21%
2660
10%
760
44%
760
21%
1657
December11th to 20thNight
33%
759
24%
3174
14%
759
48%
759
21%
1848
December21st to endNight
32%
827
15%
4764
13%
817
46%
817
14%
2682

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
14%5%25%5%35%5%5%7%43%
78552
Night
15%6%25%5%3445%7%44%
80839
TransparencyDay
40%5%11%24%17%4
78271
Night
39%411%23%18%4
80639
SeeingDay
19%10%26%25%14%5%
14064
Night
17%9%27%31%14%1
23902

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 10thDay
17%5%33323446%50%
2818
11th to 20thDay
15%8%35%6%35%5%46%42%
2840
21st to endDay
19%9%35%4345%45%39%
3124
February1st to 10thDay
13%6%35%6%46%46%7%41%
1710
11th to 20thDay
19%6%35%43345%6%43%
1680
21st to endDay
19%7%35%5%35%45%7%37%
1614
March1st to 10thDay
14%425%5%33447%50%
1980
11th to 20thDay
16%6%25%44445%7%41%
1980
21st to endDay
17%5%46%6%45%447%38%
2178
April1st to 10thDay
11%4245%35%45%7%50%
2143
11th to 20thDay
13%5%25%43445%7%48%
2134
21st to endDay
17%5%35%5%4445%6%42%
2160
May1st to 10thDay
14%6%345%35%5%7%8%40%
2333
11th to 20thDay
18%6%25%5%35%7%6%7%37%
2301
21st to endDay
15%426%5%35%5%5%9%40%
2695
June1st to 10thDay
11%5%245%35%6%6%9%44%
2520
11th to 20thDay
11%5%245%37%5%7%10%40%
2520
21st to endDay
8%325%6%45%6%7%10%43%
2520
July1st to 10thDay
10%5%35%6%46%6%7%9%40%
2449
11th to 20thDay
6%425%5%46%7%8%12%41%
2340
21st to endDay
10%5%25%7%46%6%9%10%36%
2547
August1st to 10thDay
11%5%26%7%5%6%6%6%10%35%
2327
11th to 20thDay
12%6%26%6%45%6%9%9%34%
2238
21st to endDay
10%5%25%5%36%5%6%9%42%
2376
September1st to 10thDay
13%6%25%5%35%5%5%8%44%
2160
11th to 20thDay
11%6%25%4345%5%8%45%
2119
21st to endDay
20%7%245%25%5%47%38%
1900
October1st to 10thDay
15%5%25%42435%6%48%
1800
11th to 20thDay
16%424434445%51%
1800
21st to endDay
14%5%25%433346%51%
1980
November1st to 10thDay
13%4135%24346%55%
1857
11th to 20thDay
14%5%2332445%6%51%
1687
21st to endDay
15%42443345%6%50%
1520
December1st to 10thDay
16%6%25%4346%47%41%
1520
11th to 20thDay
16%6%24433445%51%
1910
21st to endDay
19%7%36%5%345%5%7%38%
2772
January1st to 10thNight
13%7%25%424445%49%
4109
11th to 20thNight
18%6%25%433335%47%
4120
21st to endNight
20%8%35%424345%43%
4532
February1st to 10thNight
14%7%25%436%5%5%7%43%
2470
11th to 20thNight
19%8%34323346%43%
2384
21st to endNight
16%7%345%34436%44%
1837
March1st to 10thNight
13%5%25%4245%46%50%
1987
11th to 20thNight
19%6%3442445%7%42%
1980
21st to endNight
16%5%46%5%24447%43%
2178
April1st to 10thNight
13%6%35%5%2445%8%45%
1815
11th to 20thNight
11%425%5%245%5%8%49%
1775
21st to endNight
15%5%2443446%8%45%
1800
May1st to 10thNight
14%8%344345%5%8%40%
1641
11th to 20thNight
18%6%245%35%6%7%8%36%
1592
21st to endNight
14%6%34446%5%6%9%41%
1576
June1st to 10thNight
10%425%5%35%6%7%10%44%
1440
11th to 20thNight
10%5%25%6%35%5%7%9%41%
1440
21st to endNight
8%425%5%37%5%8%10%43%
1440
July1st to 10thNight
9%6%26%6%35%6%6%8%44%
1505
11th to 20thNight
5%425%5%45%7%8%11%44%
1620
21st to endNight
8%5%25%5%47%7%8%11%38%
1771
August1st to 10thNight
10%426%7%37%6%6%9%40%
1611
11th to 20thNight
13%6%27%7%35%6%6%8%37%
1643
21st to endNight
10%6%36%7%45%5%6%12%36%
1980
September1st to 10thNight
15%5%25%435%5%5%8%44%
1800
11th to 20thNight
11%6%35%5%3445%8%47%
1838
21st to endNight
21%6%35%423446%41%
2059
October1st to 10thNight
18%5%24423446%46%
2160
11th to 20thNight
16%5%25%43335%6%48%
2160
21st to endNight
14%5%245%24346%51%
2376
November1st to 10thNight
13%5%25%5%23445%53%
2221
11th to 20thNight
14%425%43445%6%50%
2490
21st to endNight
13%4135%345%5%6%50%
2660
December1st to 10thNight
16%8%35%5%3445%5%42%
2660
11th to 20thNight
17%6%34423445%47%
3285
21st to endNight
16%6%25%5%345%6%7%40%
4884

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 10thDay
37%35%31%17%5%
2819
11th to 20thDay
43%37%20%20%7%
2840
21st to endDay
48%39%22%16%3
3124
February1st to 10thDay
42%49%27%15%3
1710
11th to 20thDay
43%37%21%21%5%
1689
21st to endDay
48%311%16%17%5%
1614
March1st to 10thDay
36%49%23%22%6%
1980
11th to 20thDay
43%5%10%19%16%7%
1980
21st to endDay
47%5%8%19%17%5%
2178
April1st to 10thDay
34%410%24%19%9%
2143
11th to 20thDay
36%311%20%23%6%
2134
21st to endDay
43%411%23%15%5%
2160
May1st to 10thDay
40%6%16%20%16%3
2333
11th to 20thDay
44%7%13%23%11%2
2305
21st to endDay
41%5%15%26%13%
2695
June1st to 10thDay
35%6%16%27%14%2
2520
11th to 20thDay
39%6%16%21%16%2
2520
21st to endDay
34%7%16%26%16%2
2520
July1st to 10thDay
39%6%13%22%16%3
2382
11th to 20thDay
32%7%18%28%13%2
2271
21st to endDay
38%8%13%25%14%1
2405
August1st to 10thDay
43%7%15%25%9%1
2314
11th to 20thDay
43%8%14%22%12%1
2238
21st to endDay
38%6%16%25%13%3
2376
September1st to 10thDay
39%5%13%20%19%4
2160
11th to 20thDay
36%5%7%28%20%4
2119
21st to endDay
46%5%9%19%17%3
1900
October1st to 10thDay
38%39%26%20%4
1800
11th to 20thDay
37%38%26%23%4
1800
21st to endDay
36%36%27%22%6%
1980
November1st to 10thDay
33%38%24%28%5%
1857
11th to 20thDay
34%49%23%22%8%
1687
21st to endDay
35%49%24%24%4
1520
December1st to 10thDay
43%411%24%14%4
1520
11th to 20thDay
37%37%30%16%6%
1906
21st to endDay
46%311%26%13%1
2772
January1st to 10thNight
38%37%24%22%5%
4109
11th to 20thNight
41%27%21%23%5%
4120
21st to endNight
46%26%24%18%4
4532
February1st to 10thNight
41%410%25%17%3
2470
11th to 20thNight
44%37%20%19%7%
2386
21st to endNight
42%39%21%17%6%
1837
March1st to 10thNight
35%48%25%23%5%
1987
11th to 20thNight
42%39%21%20%4
1980
21st to endNight
42%410%22%17%6%
2178
April1st to 10thNight
39%49%19%22%7%
1815
11th to 20thNight
33%412%22%22%6%
1775
21st to endNight
37%413%25%16%6%
1800
May1st to 10thNight
42%5%13%22%14%4
1641
11th to 20thNight
43%6%14%20%13%3
1593
21st to endNight
40%7%15%24%13%1
1577
June1st to 10thNight
34%6%14%29%16%1
1440
11th to 20thNight
38%7%19%21%14%2
1440
21st to endNight
33%8%16%22%18%3
1440
July1st to 10thNight
39%7%16%19%15%4
1462
11th to 20thNight
31%9%21%25%12%2
1566
21st to endNight
35%9%18%25%12%1
1672
August1st to 10thNight
39%8%18%23%12%1
1600
11th to 20thNight
43%6%15%22%13%1
1643
21st to endNight
42%5%17%22%11%2
1980
September1st to 10thNight
39%6%13%21%15%6%
1800
11th to 20thNight
36%5%10%25%21%3
1838
21st to endNight
45%5%8%21%17%3
2059
October1st to 10thNight
40%49%25%19%3
2160
11th to 20thNight
38%46%25%22%5%
2160
21st to endNight
35%38%25%24%6%
2376
November1st to 10thNight
35%47%23%24%6%
2221
11th to 20thNight
37%38%20%25%8%
2490
21st to endNight
35%38%25%22%6%
2660
December1st to 10thNight
43%49%24%16%4
2660
11th to 20thNight
40%39%22%21%6%
3288
21st to endNight
43%411%25%16%2
4884

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 10thDay
24%21%30%20%5%
267
11th to 20thDay
27%25%32%13%3
270
21st to endDay
27%19%38%13%3
297
February1st to 10thDay
23%19%41%11%5%
270
11th to 20thDay
39%22%27%10%2
287
21st to endDay
30%18%27%21%3
382
March1st to 10thDay
21%17%36%20%5%
420
11th to 20thDay
22%18%35%17%7%
420
21st to endDay
24%18%34%18%6%1
462
April1st to 10thDay
22%18%31%20%9%1
420
11th to 20thDay
20%13%30%23%11%4
412
21st to endDay
23%11%33%22%8%2
420
May1st to 10thDay
22%14%31%22%9%3
423
11th to 20thDay
21%10%29%24%12%4
447
21st to endDay
18%424%29%20%4
485
June1st to 10thDay
14%424%32%21%5%
450
11th to 20thDay
14%6%26%30%16%8%
450
21st to endDay
9%5%26%34%20%6%
450
July1st to 10thDay
12%216%33%26%10%
445
11th to 20thDay
7%313%37%28%11%
444
21st to endDay
11%417%33%24%10%
488
August1st to 10thDay
12%317%29%26%12%
446
11th to 20thDay
13%317%30%27%12%
439
21st to endDay
12%317%30%22%16%
495
September1st to 10thDay
15%5%15%24%23%17%
450
11th to 20thDay
14%415%35%22%11%
450
21st to endDay
27%5%22%30%10%6%
450
October1st to 10thDay
20%5%22%28%17%8%
450
11th to 20thDay
16%11%24%27%19%3
450
21st to endDay
17%12%33%26%9%3
495
November1st to 10thDay
18%8%27%29%14%4
455
11th to 20thDay
18%13%32%25%9%3
337
21st to endDay
18%13%37%22%9%1
180
December1st to 10thDay
22%16%41%13%8%1
180
11th to 20thDay
24%14%31%21%8%2
180
21st to endDay
28%16%32%15%9%1
198
January1st to 10thNight
20%14%39%24%3
760
11th to 20thNight
21%14%34%28%4
760
21st to endNight
19%15%40%24%2
836
February1st to 10thNight
18%12%39%28%3
760
11th to 20thNight
25%17%37%19%2
743
21st to endNight
23%16%37%22%2
628
March1st to 10thNight
17%16%38%26%3
723
11th to 20thNight
22%15%35%21%6%1
720
21st to endNight
19%14%35%27%6%
792
April1st to 10thNight
17%16%36%24%6%
720
11th to 20thNight
14%12%35%29%9%
711
21st to endNight
17%10%33%32%8%
720
May1st to 10thNight
19%8%31%30%12%
561
11th to 20thNight
21%324%34%17%1
531
21st to endNight
15%218%39%23%3
416
June1st to 10thNight
11%118%44%25%1
360
11th to 20thNight
10%5%14%43%26%2
360
21st to endNight
8%320%45%23%1
360
July1st to 10thNight
12%215%37%30%5%
412
11th to 20thNight
7%210%41%37%4
522
21st to endNight
9%213%42%30%4
591
August1st to 10thNight
12%29%42%32%4
537
11th to 20thNight
16%38%39%30%3
579
21st to endNight
12%312%37%31%5%
792
September1st to 10thNight
17%213%32%31%6%
720
11th to 20thNight
13%415%34%30%4
720
21st to endNight
23%418%32%21%1
720
October1st to 10thNight
20%419%30%23%4
720
11th to 20thNight
18%8%24%33%16%1
720
21st to endNight
17%8%30%33%11%1
792
November1st to 10thNight
15%7%29%33%14%2
740
11th to 20thNight
16%11%33%31%8%
760
21st to endNight
15%9%33%33%9%1
760
December1st to 10thNight
21%11%34%27%7%
760
11th to 20thNight
18%9%35%32%6%
760
21st to endNight
21%10%30%34%4
836
Page generated at 2024-02-27 06:30:17. Version ac07

Copyright © 2024 Attilla Danko.


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