Lac Sacacomie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lac Sacacomie clear sky chart from 2005-11-05 to 2017-10-31.

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
27%
14741
14%
47354
7%
14709
36%
14709
17%
33347

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%
720
11%
2506
3%
716
25%
716
11%
1898
January16th to endNight
20%
768
12%
2688
5%
768
29%
768
12%
1989
February1st to 15thNight
21%
704
11%
2343
3%
701
31%
701
13%
1733
February16th to endNight
20%
631
15%
1893
6%
631
33%
631
15%
1384
March1st to 15thNight
20%
720
14%
2159
8%
720
27%
720
14%
1608
March16th to endNight
27%
768
20%
2001
7%
768
36%
768
20%
1399
April1st to 15thNight
23%
718
17%
1796
5%
718
29%
718
18%
1354
April16th to endNight
24%
595
16%
1675
4%
595
32%
595
20%
1149
May1st to 15thNight
30%
390
14%
1470
12%
390
40%
390
16%
1007
May16th to endNight
26%
375
12%
1497
10%
374
39%
374
17%
1000
June1st to 15thNight
31%
360
7%
1440
4%
360
39%
360
14%
984
June16th to endNight
36%
360
7%
1440
6%
360
40%
360
15%
966
July1st to 15thNight
43%
340
9%
1360
14%
340
47%
340
22%
818
July16th to endNight
43%
376
11%
1418
11%
354
49%
354
22%
861
August1st to 15thNight
53%
362
13%
1433
15%
360
57%
360
19%
895
August16th to endNight
46%
721
18%
1867
9%
721
50%
721
32%
1196
September1st to 15thNight
41%
720
14%
1800
6%
720
44%
720
30%
1227
September16th to endNight
41%
717
20%
1980
12%
717
47%
717
31%
1244
October1st to 15thNight
28%
720
19%
2106
9%
720
40%
720
21%
1429
October16th to endNight
23%
768
13%
2483
7%
768
31%
768
16%
1780
November1st to 15thNight
28%
700
17%
2277
10%
700
38%
700
17%
1602
November16th to endNight
22%
720
14%
2514
8%
720
31%
720
11%
1846
December1st to 15thNight
19%
720
10%
2520
3%
720
27%
720
11%
1894
December16th to endNight
13%
768
12%
2688
3%
768
24%
768
9%
2084

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
19%9%36%6%35%446%30%
48399
Night
17%9%46%5%34446%33%
47524
TransparencyDay
53%6%11%18%9%1
48086
Night
51%5%12%20%9%1
47355
SeeingDay
22%13%29%22%9%2
5724
Night
23%11%30%25%9%
14741

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%14%5%8%8%3444424%
1432
16th to endDay
12%13%5%9%8%25%445%27%
1536
February1st to 15thDay
10%16%5%9%8%46%44425%
1515
16th to endDay
15%16%7%8%6%3434426%
1580
March1st to 15thDay
15%12%48%6%45%35%428%
1790
16th to endDay
15%10%45%6%34345%36%
2220
April1st to 15thDay
22%11%35%5%23346%31%
2152
16th to endDay
21%8%36%423345%35%
2284
May1st to 15thDay
23%9%36%5%34335%31%
2491
16th to endDay
23%6%36%6%2445%6%29%
2618
June1st to 15thDay
23%7%36%5%25%5%5%7%27%
2520
16th to endDay
21%7%36%7%35%5%5%7%25%
2520
July1st to 15thDay
16%6%37%6%46%5%6%7%30%
2520
16th to endDay
14%6%27%7%36%5%6%8%30%
2654
August1st to 15thDay
18%7%26%6%46%6%6%8%25%
2505
16th to endDay
12%5%25%5%35%6%6%8%36%
2333
September1st to 15thDay
17%5%26%6%3445%7%37%
2160
16th to endDay
17%5%25%424336%44%
1980
October1st to 15thDay
25%7%25%425%35%5%30%
1851
16th to endDay
24%12%46%5%33446%23%
1738
November1st to 15thDay
18%12%48%5%34346%29%
1581
16th to endDay
22%13%45%5%2333430%
1443
December1st to 15thDay
25%14%46%5%3433424%
1440
16th to endDay
22%15%47%6%34335%23%
1536
January1st to 15thNight
16%15%6%8%5%34445%25%
2506
16th to endNight
11%13%5%9%8%35%445%27%
2688
February1st to 15thNight
8%12%6%9%7%46%446%27%
2341
16th to endNight
15%12%48%6%34446%30%
1893
March1st to 15thNight
17%12%48%6%34345%28%
2147
16th to endNight
12%9%46%424435%39%
2001
April1st to 15thNight
23%8%45%5%2445%5%31%
1796
16th to endNight
21%6%25%42335%6%37%
1675
May1st to 15thNight
22%7%35%5%24435%35%
1470
16th to endNight
23%5%35%424347%35%
1495
June1st to 15thNight
22%7%35%5%2435%5%33%
1440
16th to endNight
19%5%35%5%35%5%5%7%33%
1440
July1st to 15thNight
13%425%4245%5%9%42%
1440
16th to endNight
14%425%5%25%45%7%43%
1514
August1st to 15thNight
12%5%25%435%6%5%8%40%
1443
16th to endNight
13%5%24424447%47%
1867
September1st to 15thNight
15%5%2442445%6%43%
1800
16th to endNight
17%413323346%47%
1980
October1st to 15thNight
18%7%25%424436%40%
2106
16th to endNight
25%7%36%423446%31%
2483
November1st to 15thNight
19%8%26%5%2445%5%33%
2277
16th to endNight
21%13%47%5%24335%28%
2514
December1st to 15thNight
21%14%47%434445%25%
2520
16th to endNight
21%15%6%7%6%34345%22%
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
62%5%8%15%7%
1433
16th to endDay
58%5%7%18%8%1
1536
February1st to 15thDay
60%49%17%6%
1517
16th to endDay
61%37%16%9%1
1580
March1st to 15thDay
58%49%15%11%1
1800
16th to endDay
49%5%8%18%13%4
2220
April1st to 15thDay
54%47%17%11%3
2152
16th to endDay
50%48%18%14%3
2284
May1st to 15thDay
54%5%8%17%11%2
2491
16th to endDay
55%6%10%16%10%1
2622
June1st to 15thDay
54%7%11%16%9%1
2520
16th to endDay
56%6%10%17%7%
2520
July1st to 15thDay
48%7%14%19%8%
2371
16th to endDay
49%8%14%18%7%
2487
August1st to 15thDay
51%10%15%18%4
2491
16th to endDay
39%9%16%24%9%
2333
September1st to 15thDay
44%6%16%22%10%
2160
16th to endDay
41%412%30%10%
1980
October1st to 15thDay
53%411%23%6%
1851
16th to endDay
59%5%12%16%5%
1738
November1st to 15thDay
55%5%11%17%8%
1581
16th to endDay
57%410%19%8%
1443
December1st to 15thDay
63%311%17%3
1440
16th to endDay
63%49%12%9%
1536
January1st to 15thNight
60%410%16%6%
2506
16th to endNight
58%49%16%8%1
2688
February1st to 15thNight
57%411%18%7%
2343
16th to endNight
55%39%17%11%1
1893
March1st to 15thNight
56%5%8%17%10%1
2160
16th to endNight
47%49%19%16%3
2001
April1st to 15thNight
54%46%19%13%2
1796
16th to endNight
47%49%20%14%3
1675
May1st to 15thNight
50%5%10%16%13%3
1470
16th to endNight
48%6%11%20%11%1
1497
June1st to 15thNight
50%6%14%18%9%
1440
16th to endNight
49%6%11%18%12%
1440
July1st to 15thNight
38%7%18%22%12%
1360
16th to endNight
40%5%18%24%9%
1418
August1st to 15thNight
41%8%18%25%6%
1433
16th to endNight
36%5%18%29%9%
1867
September1st to 15thNight
40%5%15%26%11%
1800
16th to endNight
37%315%31%10%
1980
October1st to 15thNight
46%5%11%24%11%
2106
16th to endNight
53%413%21%7%
2483
November1st to 15thNight
50%5%12%19%9%1
2277
16th to endNight
59%310%18%7%
2514
December1st to 15thNight
60%5%12%17%4
2520
16th to endNight
64%48%14%7%
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
21%15%36%23%3
60
16th to endDay
21%14%39%17%43
64
February1st to 15thDay
24%24%34%15%1
82
16th to endDay
26%18%30%18%5%
239
March1st to 15thDay
24%15%32%21%4
270
16th to endDay
20%19%28%19%9%3
288
April1st to 15thDay
27%18%27%18%7%1
270
16th to endDay
25%17%32%12%8%3
270
May1st to 15thDay
30%15%24%20%6%2
288
16th to endDay
24%18%31%17%6%1
331
June1st to 15thDay
25%13%33%19%7%
315
16th to endDay
22%10%33%25%6%1
315
July1st to 15thDay
15%9%35%26%9%3
305
16th to endDay
15%5%28%34%14%1
326
August1st to 15thDay
19%5%29%27%14%4
313
16th to endDay
12%8%25%28%15%8%
332
September1st to 15thDay
19%8%26%22%16%6%
315
16th to endDay
15%10%29%21%15%7%
314
October1st to 15thDay
25%12%27%20%10%2
315
16th to endDay
31%13%27%19%8%
290
November1st to 15thDay
19%14%27%25%11%1
235
16th to endDay
31%20%23%17%6%
63
December1st to 15thDay
36%6%31%18%33
60
16th to endDay
37%17%34%10%
64
January1st to 15thNight
25%13%35%20%5%
720
16th to endNight
19%11%35%25%7%
768
February1st to 15thNight
16%13%37%25%7%
704
16th to endNight
22%14%34%23%5%
631
March1st to 15thNight
26%13%33%22%4
720
16th to endNight
18%17%30%23%8%1
768
April1st to 15thNight
28%13%28%24%5%
718
16th to endNight
24%15%31%21%7%
595
May1st to 15thNight
26%8%29%25%8%
390
16th to endNight
24%8%35%23%8%
375
June1st to 15thNight
25%8%27%30%8%
360
16th to endNight
20%431%31%11%
360
July1st to 15thNight
13%331%32%17%1
340
16th to endNight
16%329%34%15%
376
August1st to 15thNight
14%220%40%20%1
362
16th to endNight
15%426%33%18%1
721
September1st to 15thNight
18%429%32%13%1
720
16th to endNight
19%8%27%25%17%1
717
October1st to 15thNight
20%12%30%25%9%
720
16th to endNight
30%11%29%20%7%
768
November1st to 15thNight
25%10%29%24%9%1
700
16th to endNight
25%18%25%22%6%2
720
December1st to 15thNight
30%11%31%21%4
720
16th to endNight
31%13%29%20%41
768
Page generated at 2017-11-01 17:23:40. Version ac04

Copyright 2017 A. Danko


Lac Sacacomie Clear Sky Chart |Charts Home