Observatoire Laforge-1
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatoire Laforge-1 clear sky chart from 2005-11-05 to 2017-09-18.

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
30%
14794
5%
46667
4%
14762
31%
14762
9%
39395

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
24%
930
2%
2864
2%
925
25%
925
4%
2635
January16th to endNight
35%
838
8%
2790
6%
838
37%
838
7%
2397
February1st to 15thNight
42%
704
5%
2462
5%
701
44%
701
7%
2077
February16th to endNight
38%
631
7%
1991
8%
631
39%
631
9%
1668
March1st to 15thNight
41%
719
11%
2160
8%
719
44%
719
14%
1693
March16th to endNight
35%
768
10%
2009
5%
768
37%
768
13%
1642
April1st to 15thNight
33%
676
9%
1754
6%
676
35%
676
13%
1420
April16th to endNight
39%
438
13%
1518
13%
438
43%
438
16%
1140
May1st to 15thNight
34%
360
6%
1374
6%
360
36%
360
12%
1042
May16th to endNight
36%
374
0%
1252
0%
374
36%
374
18%
895
June1st to 15thNight
43%
360
0%
1080
0%
360
43%
360
21%
766
June16th to endNight
41%
360
0%
1080
0%
360
41%
360
19%
792
July1st to 15thNight
37%
340
0%
1020
0%
340
37%
340
15%
788
July16th to endNight
44%
376
1%
1198
0%
354
44%
354
13%
931
August1st to 15thNight
42%
359
5%
1430
8%
357
42%
357
10%
1113
August16th to endNight
35%
491
6%
1637
6%
491
37%
491
11%
1313
September1st to 15thNight
27%
720
7%
1800
4%
720
29%
720
12%
1513
September16th to endNight
20%
669
6%
1841
2%
669
22%
669
10%
1538
October1st to 15thNight
18%
660
7%
2010
5%
660
21%
660
7%
1743
October16th to endNight
15%
704
3%
2288
3%
704
16%
704
4%
2096
November1st to 15thNight
15%
717
1%
2529
1%
717
16%
717
2%
2355
November16th to endNight
16%
750
2%
2700
2%
750
17%
750
2%
2513
December1st to 15thNight
16%
858
1%
2808
0%
858
16%
858
2%
2631
December16th to endNight
32%
992
6%
3072
5%
992
33%
992
6%
2694

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
20%14%6%9%7%45%5%45%16%
48161
Night
16%15%6%10%8%46%5%4415%
46806
TransparencyDay
69%6%8%11%3
47816
Night
70%6%8%10%3
46669
SeeingDay
28%6%21%23%14%5%
6895
Night
23%6%24%27%14%3
14796

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
11%17%9%12%9%6%8%7%6%45%
1074
16th to endDay
6%13%7%14%11%6%9%8%9%5%7%
1432
February1st to 15thDay
39%5%12%14%10%13%12%9%45%
1400
16th to endDay
6%13%7%13%10%8%11%11%6%46%
1479
March1st to 15thDay
8%9%6%9%10%6%9%9%9%5%14%
1790
16th to endDay
8%14%7%12%9%6%7%8%5%5%13%
2213
April1st to 15thDay
15%15%6%10%8%5%6%45%5%16%
2194
16th to endDay
14%14%7%10%8%3433325%
2454
May1st to 15thDay
23%15%6%9%6%23335%21%
2577
16th to endDay
17%14%48%6%3445%7%23%
2859
June1st to 15thDay
20%11%35%5%245%46%30%
2880
16th to endDay
23%9%37%6%3445%6%24%
2880
July1st to 15thDay
27%10%48%7%34445%19%
2880
16th to endDay
28%10%48%7%45%5%35%15%
2885
August1st to 15thDay
26%11%46%6%45%6%45%16%
2520
16th to endDay
30%13%5%6%6%34445%15%
2551
September1st to 15thDay
30%13%48%6%2333418%
2160
16th to endDay
32%17%46%5%3224414%
1844
October1st to 15thDay
27%23%5%7%43333411%
1617
16th to endDay
32%21%10%8%5%222228%
1584
November1st to 15thDay
24%23%11%12%7%232226%
1326
16th to endDay
17%24%12%14%9%422235%
1260
December1st to 15thDay
12%17%7%15%12%7%7%6%325%
1150
16th to endDay
10%13%7%11%13%7%12%7%5%36%
1152
January1st to 15thNight
12%18%7%14%11%6%9%8%5%22
2864
16th to endNight
7%14%7%12%11%6%11%9%6%5%7%
2790
February1st to 15thNight
39%6%13%12%8%12%12%9%5%6%
2460
16th to endNight
7%15%6%11%11%6%8%8%7%5%10%
1991
March1st to 15thNight
6%11%6%10%8%48%9%6%7%18%
2147
16th to endNight
9%13%6%12%7%5%7%6%4421%
2009
April1st to 15thNight
14%15%7%9%7%36%445%22%
1754
16th to endNight
13%11%6%7%7%4444430%
1518
May1st to 15thNight
22%13%5%7%6%35%23425%
1374
16th to endNight
13%12%47%5%34445%33%
1252
June1st to 15thNight
20%8%25%434346%35%
1080
16th to endNight
21%8%25%5%24447%32%
1080
July1st to 15thNight
24%7%36%5%445%46%26%
1080
16th to endNight
23%8%46%5%45%36%6%24%
1282
August1st to 15thNight
22%9%48%6%35%35%7%23%
1440
16th to endNight
26%10%38%6%3335%6%22%
1637
September1st to 15thNight
26%12%48%5%3433422%
1800
16th to endNight
32%14%46%424335%18%
1841
October1st to 15thNight
28%23%36%42323416%
2010
16th to endNight
30%22%7%10%6%232238%
2288
November1st to 15thNight
25%22%10%12%7%332325%
2529
16th to endNight
17%22%9%15%9%45%3236%
2700
December1st to 15thNight
11%19%10%17%12%5%7%5%315%
2808
16th to endNight
10%15%6%12%11%6%9%8%6%39%
3072

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
79%36%8%2
1075
16th to endDay
71%6%7%9%5%
1432
February1st to 15thDay
71%7%8%9%3
1402
16th to endDay
75%6%7%7%2
1479
March1st to 15thDay
63%6%6%16%6%
1800
16th to endDay
70%5%7%9%5%
2213
April1st to 15thDay
68%5%7%14%4
2194
16th to endDay
64%47%16%6%
2454
May1st to 15thDay
67%37%15%5%
2577
16th to endDay
60%6%11%17%4
2863
June1st to 15thDay
55%6%10%18%9%
2880
16th to endDay
60%6%11%15%6%
2880
July1st to 15thDay
65%7%10%14%3
2711
16th to endDay
69%8%10%9%1
2706
August1st to 15thDay
67%9%12%9%1
2506
16th to endDay
70%7%11%8%1
2551
September1st to 15thDay
70%5%10%11%2
2160
16th to endDay
74%49%10%
1844
October1st to 15thDay
76%5%7%8%1
1617
16th to endDay
84%46%4
1584
November1st to 15thDay
85%45%21
1326
16th to endDay
86%3341
1260
December1st to 15thDay
82%7%6%2
1150
16th to endDay
78%47%6%1
1152
January1st to 15thNight
83%5%5%41
2864
16th to endNight
73%6%5%8%5%
2790
February1st to 15thNight
69%8%7%10%3
2462
16th to endNight
69%5%8%10%4
1991
March1st to 15thNight
60%6%10%14%8%
2160
16th to endNight
65%5%6%15%6%
2009
April1st to 15thNight
64%5%8%14%5%1
1754
16th to endNight
56%6%7%17%10%
1518
May1st to 15thNight
63%27%18%8%
1374
16th to endNight
52%5%15%19%7%
1254
June1st to 15thNight
51%412%21%10%
1080
16th to endNight
50%8%11%19%9%
1080
July1st to 15thNight
58%7%12%19%3
1020
16th to endNight
57%9%15%16%
1198
August1st to 15thNight
60%8%14%14%
1430
16th to endNight
63%7%13%14%1
1637
September1st to 15thNight
66%6%9%14%2
1800
16th to endNight
69%5%12%10%2
1841
October1st to 15thNight
73%6%7%10%1
2010
16th to endNight
82%5%6%5%
2288
November1st to 15thNight
85%45%21
2529
16th to endNight
84%5%431
2700
December1st to 15thNight
85%5%421
2808
16th to endNight
74%6%6%8%2
3072

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
8%16%35%31%6%1
60
16th to endDay
21%325%25%18%6%
64
February1st to 15thDay
15%18%35%33%6%
60
16th to endDay
10%6%25%30%20%6%
159
March1st to 15thDay
13%424%30%21%5%
270
16th to endDay
13%6%29%30%14%5%
288
April1st to 15thDay
20%427%25%14%7%
270
16th to endDay
22%8%23%25%12%7%
270
May1st to 15thDay
27%7%21%20%16%5%
354
16th to endDay
23%6%24%29%12%3
573
June1st to 15thDay
29%420%21%16%6%
675
16th to endDay
28%8%20%24%14%4
675
July1st to 15thDay
32%6%17%22%13%6%
645
16th to endDay
34%416%22%16%5%
555
August1st to 15thDay
34%5%13%16%17%12%
313
16th to endDay
34%7%17%21%9%8%
332
September1st to 15thDay
39%10%19%19%7%3
315
16th to endDay
38%10%27%16%5%1
262
October1st to 15thDay
40%9%19%18%9%2
244
16th to endDay
45%8%16%12%10%5%
240
November1st to 15thDay
48%425%12%6%2
87
16th to endDay
26%8%30%18%13%3
60
December1st to 15thDay
20%5%25%21%20%8%
60
16th to endDay
15%334%34%6%6%
64
January1st to 15thNight
19%7%25%25%15%5%
930
16th to endNight
11%423%33%21%5%
838
February1st to 15thNight
6%424%35%22%7%
704
16th to endNight
14%221%33%22%4
631
March1st to 15thNight
10%5%27%32%21%3
720
16th to endNight
14%5%30%32%13%3
768
April1st to 15thNight
22%5%25%30%14%2
676
16th to endNight
16%6%26%31%14%2
438
May1st to 15thNight
29%6%20%29%12%1
360
16th to endNight
21%6%28%34%8%
375
June1st to 15thNight
24%419%32%16%1
360
16th to endNight
25%5%20%31%14%1
360
July1st to 15thNight
28%5%20%30%13%2
340
16th to endNight
23%320%26%22%3
376
August1st to 15thNight
25%216%27%23%3
359
16th to endNight
30%420%27%14%2
491
September1st to 15thNight
33%9%22%23%10%
720
16th to endNight
39%9%25%18%5%1
669
October1st to 15thNight
39%9%26%16%7%
660
16th to endNight
42%6%20%16%10%3
704
November1st to 15thNight
37%9%22%18%9%3
717
16th to endNight
27%10%27%22%8%4
750
December1st to 15thNight
18%9%32%26%10%2
858
16th to endNight
18%423%31%18%3
992
Page generated at 2017-09-19 07:32:30. Version ac04

Copyright 2017 A. Danko


Observatoire Laforge-1 Clear Sky Chart | Charts Home