Isle Pierre
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Isle Pierre clear sky chart from 2005-11-05 to 2017-12-02.

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
39%
15103
8%
47722
6%
15075
42%
15075
15%
35190

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
26%
799
5%
2736
4%
796
29%
796
7%
2293
January16th to endNight
32%
800
9%
2880
7%
800
35%
800
9%
2273
February1st to 15thNight
32%
704
7%
2399
6%
704
35%
704
11%
1872
February16th to endNight
42%
632
11%
2053
9%
632
46%
632
16%
1470
March1st to 15thNight
30%
720
10%
2109
6%
720
33%
720
14%
1621
March16th to endNight
43%
768
10%
2061
6%
767
45%
767
18%
1549
April1st to 15thNight
42%
650
9%
1730
6%
650
44%
650
18%
1305
April16th to endNight
38%
438
9%
1518
8%
438
43%
438
14%
1101
May1st to 15thNight
42%
359
5%
1410
3%
359
43%
359
15%
975
May16th to endNight
45%
374
0%
1234
0%
374
45%
374
17%
868
June1st to 15thNight
43%
360
0%
1080
0%
360
43%
360
19%
766
June16th to endNight
48%
360
0%
1080
0%
360
48%
360
21%
756
July1st to 15thNight
47%
340
0%
1078
0%
340
47%
340
20%
735
July16th to endNight
60%
376
2%
1239
1%
354
62%
354
31%
687
August1st to 15thNight
67%
360
10%
1378
13%
358
69%
358
30%
734
August16th to endNight
50%
550
11%
1696
9%
550
53%
550
22%
1147
September1st to 15thNight
59%
708
16%
1788
9%
708
60%
708
35%
1146
September16th to endNight
46%
716
14%
1978
8%
716
48%
716
20%
1424
October1st to 15thNight
41%
720
10%
2160
7%
720
45%
720
19%
1533
October16th to endNight
32%
768
9%
2536
4%
768
39%
768
12%
1926
November1st to 15thNight
30%
760
7%
2660
5%
760
33%
760
11%
2013
November16th to endNight
29%
907
9%
2935
5%
907
34%
907
12%
2256
December1st to 15thNight
35%
942
7%
2912
6%
942
36%
942
12%
2270
December16th to endNight
30%
992
8%
3072
4%
992
33%
992
10%
2470

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
11%10%49%8%46%5%5%6%25%
48759
Night
10%11%5%8%8%46%5%5%7%26%
47865
TransparencyDay
53%6%17%17%4
48402
Night
54%7%16%16%5%
47726
SeeingDay
14%9%26%27%17%4
7074
Night
16%7%22%31%19%2
15112

By Month

Percentage Cloud Cover NW (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%14%6%12%10%5%6%5%45%17%
1215
16th to endDay
9%13%5%11%9%5%7%5%47%22%
1344
February1st to 15thDay
13%13%49%8%345%5%7%24%
1461
16th to endDay
6%12%6%9%8%35%5%48%28%
1421
March1st to 15thDay
9%15%7%8%8%46%5%6%6%20%
1848
16th to endDay
7%12%6%9%9%48%5%6%8%21%
2158
April1st to 15thDay
8%15%6%10%9%5%7%6%5%5%19%
2214
16th to endDay
12%13%7%11%9%45%45%419%
2442
May1st to 15thDay
11%12%5%8%8%5%6%5%5%6%25%
2541
16th to endDay
12%10%410%9%47%6%5%6%22%
2876
June1st to 15thDay
13%9%49%8%5%5%5%6%6%25%
2880
16th to endDay
13%8%49%9%5%7%6%6%7%22%
2880
July1st to 15thDay
14%7%46%7%5%6%5%6%7%29%
2815
16th to endDay
8%6%37%7%47%6%7%7%35%
2846
August1st to 15thDay
5%5%27%6%45%5%7%8%39%
2574
16th to endDay
11%8%48%6%46%5%6%6%29%
2503
September1st to 15thDay
8%6%37%6%35%5%6%7%38%
2172
16th to endDay
14%9%37%7%45%6%6%6%27%
1980
October1st to 15thDay
12%11%47%7%46%6%6%7%25%
1800
16th to endDay
15%11%49%8%45%6%5%5%22%
1684
November1st to 15thDay
14%13%5%8%7%5%6%445%24%
1528
16th to endDay
8%14%5%10%10%5%7%6%5%5%18%
1339
December1st to 15thDay
13%9%5%11%8%36%45%6%25%
1086
16th to endDay
7%14%6%9%8%5%6%6%6%9%18%
1152
January1st to 15thNight
10%14%8%11%10%46%5%45%17%
2736
16th to endNight
12%12%5%9%8%46%5%6%6%21%
2880
February1st to 15thNight
12%15%5%9%7%45%445%23%
2387
16th to endNight
6%10%5%10%9%26%45%7%29%
2053
March1st to 15thNight
9%13%6%10%9%45%5%5%5%24%
2109
16th to endNight
6%10%5%9%8%5%7%7%7%7%22%
2061
April1st to 15thNight
8%14%5%9%8%47%5%45%25%
1730
16th to endNight
8%10%6%8%8%5%7%45%6%27%
1518
May1st to 15thNight
12%10%49%8%5%5%46%6%26%
1409
16th to endNight
13%8%48%7%47%6%7%8%23%
1234
June1st to 15thNight
14%6%37%6%47%5%6%9%26%
1080
16th to endNight
9%8%5%6%7%37%7%6%9%29%
1080
July1st to 15thNight
12%6%27%7%46%5%6%7%33%
1143
16th to endNight
8%424435%6%7%9%42%
1323
August1st to 15thNight
6%4235%25%46%7%50%
1385
16th to endNight
10%6%37%6%45%5%5%9%33%
1696
September1st to 15thNight
7%6%25%5%3447%7%43%
1788
16th to endNight
13%8%47%7%45%5%5%8%29%
1978
October1st to 15thNight
11%9%48%7%46%5%5%6%31%
2160
16th to endNight
15%12%47%6%5%5%6%5%6%22%
2536
November1st to 15thNight
12%11%48%8%47%6%6%6%22%
2660
16th to endNight
9%14%6%9%9%45%5%5%7%21%
2935
December1st to 15thNight
13%11%5%8%7%36%45%5%26%
2912
16th to endNight
6%13%6%13%9%5%6%5%5%7%20%
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
67%10%13%7%1
1215
16th to endDay
61%9%13%11%5%
1344
February1st to 15thDay
58%7%14%13%4
1461
16th to endDay
52%5%16%18%6%
1421
March1st to 15thDay
60%5%12%15%5%
1848
16th to endDay
55%420%14%4
2158
April1st to 15thDay
61%5%13%15%3
2214
16th to endDay
64%412%14%4
2442
May1st to 15thDay
55%415%17%6%
2541
16th to endDay
55%5%16%17%3
2880
June1st to 15thDay
52%6%15%19%6%
2880
16th to endDay
53%6%17%17%4
2880
July1st to 15thDay
47%6%17%20%7%
2651
16th to endDay
40%7%25%22%4
2667
August1st to 15thDay
37%6%25%26%4
2556
16th to endDay
48%7%20%19%3
2503
September1st to 15thDay
38%6%26%23%5%
2172
16th to endDay
51%7%16%19%3
1980
October1st to 15thDay
52%8%19%15%3
1800
16th to endDay
57%9%18%13%1
1684
November1st to 15thDay
58%6%15%12%6%
1528
16th to endDay
65%7%10%13%2
1339
December1st to 15thDay
58%9%15%14%2
1086
16th to endDay
61%9%13%11%2
1152
January1st to 15thNight
67%8%12%8%2
2736
16th to endNight
61%9%13%9%5%
2880
February1st to 15thNight
61%6%13%11%6%
2399
16th to endNight
52%6%15%17%7%
2053
March1st to 15thNight
59%5%12%15%5%1
2109
16th to endNight
53%6%18%15%5%
2065
April1st to 15thNight
55%412%20%6%
1730
16th to endNight
56%5%13%17%6%
1518
May1st to 15thNight
53%414%17%10%
1410
16th to endNight
51%5%16%21%4
1234
June1st to 15thNight
50%6%14%21%6%
1080
16th to endNight
47%7%18%21%5%
1080
July1st to 15thNight
47%6%15%19%10%1
1078
16th to endNight
31%6%29%27%5%
1239
August1st to 15thNight
29%7%20%33%8%
1378
16th to endNight
44%7%22%20%3
1696
September1st to 15thNight
35%5%20%29%8%
1788
16th to endNight
48%8%14%22%6%
1978
October1st to 15thNight
49%6%20%18%4
2160
16th to endNight
57%8%17%15%1
2536
November1st to 15thNight
57%8%17%11%5%
2660
16th to endNight
58%7%14%14%4
2935
December1st to 15thNight
59%7%14%15%2
2912
16th to endNight
62%8%13%12%3
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
10%6%10%18%40%15%
60
16th to endDay
17%9%20%25%17%10%
64
February1st to 15thDay
14%12%30%23%16%2
155
16th to endDay
11%10%23%32%14%6%
211
March1st to 15thDay
19%13%39%22%4
266
16th to endDay
15%15%29%26%12%
288
April1st to 15thDay
17%16%28%22%10%2
269
16th to endDay
19%13%35%19%9%2
270
May1st to 15thDay
18%11%27%27%12%3
318
16th to endDay
15%8%24%26%20%4
590
June1st to 15thDay
17%7%23%28%20%3
675
16th to endDay
13%6%26%30%18%4
675
July1st to 15thDay
15%7%21%29%21%4
585
16th to endDay
10%8%21%31%25%2
515
August1st to 15thDay
5%320%33%29%7%
369
16th to endDay
12%9%28%33%14%1
332
September1st to 15thDay
13%6%27%31%17%5%
315
16th to endDay
16%9%35%23%13%1
315
October1st to 15thDay
19%11%25%25%15%2
315
16th to endDay
20%10%25%25%16%1
181
November1st to 15thDay
16%10%35%18%8%10%
90
16th to endDay
8%6%31%30%14%8%
90
December1st to 15thDay
12%122%27%24%11%
62
16th to endDay
10%6%12%32%23%14%
64
January1st to 15thNight
18%11%22%27%15%3
801
16th to endNight
18%10%28%29%13%1
800
February1st to 15thNight
19%10%21%28%16%2
709
16th to endNight
13%6%19%35%21%3
632
March1st to 15thNight
14%12%29%28%11%2
720
16th to endNight
11%8%20%32%23%3
768
April1st to 15thNight
17%7%16%33%20%4
650
16th to endNight
16%7%25%30%18%2
438
May1st to 15thNight
15%7%18%36%19%2
360
16th to endNight
17%6%18%29%25%2
375
June1st to 15thNight
15%425%28%25%1
360
16th to endNight
9%224%34%26%3
360
July1st to 15thNight
15%221%31%26%2
340
16th to endNight
9%319%36%26%4
376
August1st to 15thNight
7%112%31%38%8%
360
16th to endNight
15%215%36%26%3
550
September1st to 15thNight
11%316%31%32%4
708
16th to endNight
16%6%19%31%20%4
716
October1st to 15thNight
19%5%21%31%17%4
720
16th to endNight
22%8%24%28%14%1
768
November1st to 15thNight
19%10%25%31%10%1
760
16th to endNight
19%10%27%28%10%2
907
December1st to 15thNight
19%8%22%32%15%1
942
16th to endNight
15%9%27%30%15%2
992
Page generated at 2017-12-03 08:16:37. Version ac04

Copyright 2017 A. Danko


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