Houghton Lake Observatory Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Houghton Lake Observatory Site clear sky chart from 2005-11-05 to 2018-04-23.

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
31%
16701
13%
49606
8%
16658
37%
16658
18%
35815

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
15%
975
7%
2716
3%
970
20%
970
9%
2272
January16th to endNight
15%
1040
7%
2912
2%
1040
19%
1040
9%
2411
February1st to 15thNight
16%
777
9%
2453
3%
776
22%
776
10%
1942
February16th to endNight
19%
683
10%
2049
4%
683
25%
683
10%
1638
March1st to 15thNight
26%
780
15%
2293
8%
780
32%
780
18%
1647
March16th to endNight
29%
818
18%
2274
9%
818
37%
818
23%
1568
April1st to 15thNight
26%
584
15%
1929
8%
584
34%
584
16%
1369
April16th to endNight
33%
558
20%
1672
9%
558
43%
558
24%
1099
May1st to 15thNight
33%
540
13%
1620
7%
540
40%
540
22%
1108
May16th to endNight
39%
562
15%
1547
7%
561
48%
561
28%
1013
June1st to 15thNight
42%
414
14%
1314
11%
414
47%
414
25%
830
June16th to endNight
50%
426
13%
1326
9%
426
56%
426
28%
825
July1st to 15thNight
62%
510
16%
1360
12%
510
64%
510
41%
789
July16th to endNight
58%
564
16%
1417
10%
531
62%
531
36%
880
August1st to 15thNight
60%
539
20%
1593
14%
536
65%
536
37%
913
August16th to endNight
59%
573
20%
1767
16%
573
64%
573
33%
1046
September1st to 15thNight
54%
624
20%
1884
17%
624
58%
624
35%
1094
September16th to endNight
49%
717
22%
1980
15%
717
53%
717
31%
1263
October1st to 15thNight
37%
720
18%
2046
12%
720
43%
720
23%
1412
October16th to endNight
25%
768
12%
2475
8%
768
32%
768
14%
1814
November1st to 15thNight
27%
760
16%
2471
12%
760
34%
760
17%
1759
November16th to endNight
18%
780
8%
2600
4%
780
23%
780
9%
2080
December1st to 15thNight
12%
949
5%
2899
1%
949
17%
949
7%
2461
December16th to endNight
13%
1040
6%
3009
1%
1040
17%
1040
7%
2582

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%9%47%6%35%45%6%31%
49902
Night
14%10%47%6%3445%6%31%
49774
Cloud CoverDay
14%10%47%6%35%45%7%30%
49911
Night
14%10%47%6%3445%6%31%
49779
TransparencyDay
52%6%12%18%9%
49588
Night
51%6%12%19%9%
49606
SeeingDay
18%12%30%22%11%4
6652
Night
19%11%31%26%10%1
16704

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
16%15%7%12%8%5%6%5%45%12%
1552
16th to endDay
12%16%10%14%10%5%6%43311%
1664
February1st to 15thDay
12%15%7%12%11%5%6%43416%
1738
16th to endDay
12%14%8%12%10%45%5%4318%
1710
March1st to 15thDay
14%10%5%8%9%45%445%28%
1985
16th to endDay
14%10%47%7%34445%32%
2314
April1st to 15thDay
20%12%5%5%423335%31%
2348
16th to endDay
16%9%25%5%34446%36%
2402
May1st to 15thDay
18%7%37%5%35%5%45%33%
2331
16th to endDay
11%6%25%5%35%5%5%8%40%
2567
June1st to 15thDay
13%6%26%5%35%46%8%37%
2640
16th to endDay
11%6%25%6%36%5%5%9%36%
2628
July1st to 15thDay
8%5%25%5%36%5%5%8%42%
2520
16th to endDay
9%435%5%35%6%6%9%39%
2655
August1st to 15thDay
8%425%7%46%5%6%10%38%
2356
16th to endDay
13%7%25%5%3445%7%41%
2432
September1st to 15thDay
13%6%245%3446%7%41%
2064
16th to endDay
13%5%26%5%345%5%9%37%
1980
October1st to 15thDay
20%9%36%5%3443434%
1914
16th to endDay
23%12%5%8%6%3445%5%20%
1746
November1st to 15thDay
17%12%37%5%35%446%29%
1717
16th to endDay
20%17%6%9%7%3443418%
1688
December1st to 15thDay
17%18%9%13%7%4443412%
1388
16th to endDay
20%19%9%10%7%4434411%
1563
January1st to 15thNight
18%13%6%10%7%5%6%5%4416%
2716
16th to endNight
11%14%8%12%8%46%5%5%6%15%
2912
February1st to 15thNight
12%13%7%10%9%5%6%5%5%420%
2451
16th to endNight
15%13%5%10%8%45%445%21%
2049
March1st to 15thNight
13%10%6%7%5%34435%35%
2280
16th to endNight
13%8%5%6%5%2435%6%38%
2274
April1st to 15thNight
19%11%47%5%2435%6%31%
1929
16th to endNight
16%10%2442335%5%43%
1672
May1st to 15thNight
13%5%36%7%345%6%7%35%
1620
16th to endNight
11%6%25%436%5%410%40%
1545
June1st to 15thNight
13%425%435%45%9%41%
1314
16th to endNight
8%425%5%35%5%6%8%43%
1326
July1st to 15thNight
6%32342447%9%51%
1440
16th to endNight
6%425%4345%6%8%49%
1513
August1st to 15thNight
6%414425%45%8%52%
1602
16th to endNight
10%5%143245%5%7%49%
1767
September1st to 15thNight
12%5%1321345%6%52%
1884
16th to endNight
10%6%25%4235%5%7%44%
1980
October1st to 15thNight
18%9%36%422336%39%
2046
16th to endNight
22%11%37%5%24347%27%
2475
November1st to 15thNight
13%11%37%5%35%5%5%7%31%
2471
16th to endNight
18%16%6%8%7%3445%5%19%
2600
December1st to 15thNight
18%15%7%11%7%46%445%15%
2899
16th to endNight
19%16%6%12%7%35%345%13%
3009

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%15%7%12%9%5%5%5%4413%
1552
16th to endDay
12%17%9%15%10%5%6%43411%
1664
February1st to 15thDay
12%15%6%12%12%46%43416%
1738
16th to endDay
12%14%8%11%10%35%5%5%318%
1710
March1st to 15thDay
14%10%5%8%9%35%446%27%
1995
16th to endDay
15%10%47%6%345%45%32%
2313
April1st to 15thDay
20%13%46%5%23335%31%
2348
16th to endDay
16%10%35%5%25%447%36%
2402
May1st to 15thDay
18%7%37%5%25%5%5%5%32%
2331
16th to endDay
11%5%25%5%35%45%8%40%
2567
June1st to 15thDay
12%6%36%5%35%5%6%8%37%
2640
16th to endDay
11%6%26%5%36%6%5%9%36%
2628
July1st to 15thDay
8%5%16%5%36%5%5%9%40%
2520
16th to endDay
9%436%5%36%5%7%9%39%
2655
August1st to 15thDay
8%425%7%36%6%6%10%38%
2356
16th to endDay
12%8%25%5%335%48%40%
2432
September1st to 15thDay
14%6%245%3446%7%41%
2064
16th to endDay
13%5%26%5%35%5%49%37%
1980
October1st to 15thDay
19%10%36%5%24445%34%
1914
16th to endDay
23%13%38%6%34446%20%
1746
November1st to 15thDay
17%12%47%425%45%6%29%
1717
16th to endDay
19%17%6%9%7%34335%17%
1688
December1st to 15thDay
17%18%8%13%7%34435%12%
1388
16th to endDay
20%20%8%11%8%3434411%
1563
January1st to 15thNight
18%13%6%10%7%5%6%5%4417%
2716
16th to endNight
11%14%8%12%8%46%45%6%16%
2912
February1st to 15thNight
12%12%7%9%9%46%5%5%5%20%
2444
16th to endNight
15%13%6%11%7%35%5%45%21%
2049
March1st to 15thNight
13%10%6%7%6%24445%34%
2293
16th to endNight
13%8%46%43445%6%38%
2274
April1st to 15thNight
18%11%46%5%24346%31%
1929
16th to endNight
16%9%24413445%42%
1672
May1st to 15thNight
13%5%26%8%345%5%6%36%
1619
16th to endNight
11%5%25%437%5%410%40%
1545
June1st to 15thNight
13%4245%35%45%9%41%
1314
16th to endNight
8%5%25%5%35%47%8%43%
1326
July1st to 15thNight
6%22442446%9%52%
1440
16th to endNight
6%424425%5%6%8%48%
1513
August1st to 15thNight
6%4135%2445%8%51%
1602
16th to endNight
10%5%143245%5%7%49%
1767
September1st to 15thNight
11%5%143135%46%52%
1884
16th to endNight
10%6%25%5%235%5%7%45%
1980
October1st to 15thNight
18%10%35%432336%39%
2046
16th to endNight
22%10%37%5%33347%27%
2475
November1st to 15thNight
13%12%37%5%3445%8%30%
2471
16th to endNight
18%16%6%8%7%34445%19%
2600
December1st to 15thNight
18%15%7%11%7%46%44415%
2899
16th to endNight
19%16%7%11%7%4445%414%
3009

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
72%5%9%8%3
1553
16th to endDay
76%5%8%7%2
1664
February1st to 15thDay
70%5%8%11%3
1740
16th to endDay
67%5%10%12%4
1710
March1st to 15thDay
57%6%11%16%8%
1995
16th to endDay
53%5%11%19%9%1
2314
April1st to 15thDay
56%49%18%11%
2348
16th to endDay
47%5%13%15%15%2
2402
May1st to 15thDay
50%6%9%20%9%2
2331
16th to endDay
41%7%13%24%12%1
2571
June1st to 15thDay
43%7%12%23%11%
2640
16th to endDay
42%8%15%20%12%
2628
July1st to 15thDay
36%7%13%24%16%1
2371
16th to endDay
39%8%14%21%14%2
2488
August1st to 15thDay
39%7%14%24%12%
2341
16th to endDay
41%7%12%23%13%2
2432
September1st to 15thDay
39%7%12%26%12%1
2064
16th to endDay
41%6%16%25%10%
1980
October1st to 15thDay
52%6%9%22%8%
1914
16th to endDay
64%6%12%11%4
1746
November1st to 15thDay
53%6%13%18%7%
1717
16th to endDay
69%5%11%9%3
1688
December1st to 15thDay
73%5%10%7%2
1388
16th to endDay
75%49%7%2
1563
January1st to 15thNight
68%5%9%10%5%
2716
16th to endNight
67%6%12%10%3
2912
February1st to 15thNight
63%5%9%14%5%
2453
16th to endNight
63%6%10%13%5%
2049
March1st to 15thNight
51%5%11%18%11%
2293
16th to endNight
46%5%12%22%11%1
2274
April1st to 15thNight
53%49%17%13%
1929
16th to endNight
43%5%10%20%16%3
1672
May1st to 15thNight
44%7%12%20%11%2
1620
16th to endNight
38%6%14%24%13%1
1547
June1st to 15thNight
39%6%13%23%17%
1314
16th to endNight
35%7%14%24%16%
1326
July1st to 15thNight
26%6%13%31%20%1
1360
16th to endNight
31%7%15%28%15%1
1417
August1st to 15thNight
29%6%17%30%15%
1593
16th to endNight
32%7%14%27%16%1
1767
September1st to 15thNight
30%6%13%31%16%1
1884
16th to endNight
37%6%14%32%8%
1980
October1st to 15thNight
47%410%25%11%1
2046
16th to endNight
55%5%14%17%5%
2475
November1st to 15thNight
50%7%13%18%9%
2471
16th to endNight
65%5%14%10%2
2600
December1st to 15thNight
70%6%9%10%3
2899
16th to endNight
72%5%10%8%2
3009

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
21%13%45%17%2
135
16th to endDay
31%11%38%15%2
144
February1st to 15thDay
23%28%42%4
135
16th to endDay
24%29%35%8%2
120
March1st to 15thDay
28%18%33%13%4
180
16th to endDay
23%10%32%23%7%3
352
April1st to 15thDay
29%14%28%17%8%
330
16th to endDay
21%11%32%21%10%3
289
May1st to 15thDay
25%13%30%18%7%4
288
16th to endDay
15%13%33%23%9%3
467
June1st to 15thDay
16%13%32%25%8%3
495
16th to endDay
12%12%34%25%10%3
495
July1st to 15thDay
8%9%29%28%17%6%
475
16th to endDay
10%6%30%29%14%7%
515
August1st to 15thDay
8%323%31%20%11%
329
16th to endDay
19%5%18%25%21%10%
332
September1st to 15thDay
15%420%24%22%12%
315
16th to endDay
13%7%21%30%20%7%
314
October1st to 15thDay
27%11%27%23%9%
315
16th to endDay
25%18%40%11%31
162
November1st to 15thDay
22%15%38%16%5%
135
16th to endDay
26%23%36%10%3
119
December1st to 15thDay
38%25%21%8%5%
90
16th to endDay
29%35%24%8%1
121
January1st to 15thNight
24%15%35%18%5%
975
16th to endNight
18%14%38%23%4
1040
February1st to 15thNight
18%18%35%22%4
779
16th to endNight
24%15%32%23%3
683
March1st to 15thNight
19%15%33%22%8%
780
16th to endNight
19%12%34%25%7%1
818
April1st to 15thNight
22%12%33%25%5%
584
16th to endNight
21%8%32%28%6%1
558
May1st to 15thNight
15%10%34%29%9%
540
16th to endNight
14%7%33%30%13%
563
June1st to 15thNight
14%8%30%33%11%
414
16th to endNight
9%429%38%15%1
426
July1st to 15thNight
7%321%43%22%2
510
16th to endNight
8%224%39%23%1
564
August1st to 15thNight
9%122%39%25%2
539
16th to endNight
11%321%38%23%1
573
September1st to 15thNight
13%6%22%29%21%6%
624
16th to endNight
12%6%25%30%19%4
717
October1st to 15thNight
22%8%27%29%11%1
720
16th to endNight
29%13%27%23%5%
768
November1st to 15thNight
21%11%34%22%9%1
760
16th to endNight
25%15%33%20%3
780
December1st to 15thNight
25%17%36%18%2
949
16th to endNight
26%14%35%18%3
1040
Page generated at 2018-04-24 10:03:07. Version ac04

Copyright 2018 A. Danko


Houghton Lake Observatory Site Clear Sky Chart |Charts Home