Jasper
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jasper clear sky chart from 2005-11-05 to 2017-09-16.

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%
15007
8%
46637
4%
14975
31%
14975
14%
34603

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%
922
5%
2857
3%
917
17%
917
9%
2315
January16th to endNight
15%
771
11%
2706
5%
771
24%
771
10%
2040
February1st to 15thNight
18%
699
6%
2464
4%
696
23%
696
10%
1881
February16th to endNight
28%
632
11%
1968
9%
632
33%
632
17%
1419
March1st to 15thNight
15%
720
10%
2160
3%
720
22%
720
13%
1616
March16th to endNight
25%
768
9%
2016
3%
768
29%
768
15%
1551
April1st to 15thNight
28%
698
9%
1778
3%
698
32%
698
13%
1374
April16th to endNight
30%
445
7%
1525
6%
445
32%
445
11%
1160
May1st to 15thNight
44%
359
5%
1425
4%
359
46%
359
13%
1006
May16th to endNight
40%
374
1%
1298
0%
374
41%
374
14%
977
June1st to 15thNight
37%
360
0%
1080
0%
360
37%
360
13%
849
June16th to endNight
41%
360
0%
1080
0%
360
41%
360
17%
792
July1st to 15thNight
48%
340
0%
1020
0%
340
48%
340
23%
685
July16th to endNight
51%
376
4%
1286
2%
354
53%
354
19%
835
August1st to 15thNight
59%
360
5%
1432
8%
358
60%
358
17%
939
August16th to endNight
44%
532
13%
1678
12%
532
47%
532
22%
1083
September1st to 15thNight
44%
720
12%
1800
7%
720
46%
720
26%
1264
September16th to endNight
33%
656
13%
1796
5%
656
39%
656
23%
1227
October1st to 15thNight
27%
660
9%
1993
6%
660
31%
660
14%
1506
October16th to endNight
18%
704
8%
2288
4%
704
24%
704
12%
1717
November1st to 15thNight
12%
750
7%
2461
2%
750
17%
750
11%
1820
November16th to endNight
15%
900
8%
2700
2%
900
22%
900
11%
2094
December1st to 15thNight
18%
909
9%
2754
5%
909
22%
909
12%
2108
December16th to endNight
18%
992
9%
3072
3%
992
24%
992
12%
2345

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
9%10%5%10%8%5%6%6%6%7%22%
48143
Night
5%8%48%8%47%7%7%9%27%
46780
Cloud CoverDay
10%11%5%10%8%46%6%6%7%22%
48143
Night
5%9%5%9%8%47%6%7%9%26%
46783
TransparencyDay
59%8%14%12%4
47791
Night
52%9%17%14%4
46637
SeeingDay
20%16%31%21%8%1
6568
Night
12%12%38%25%10%
15014

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
27%410%10%5%8%7%8%11%23%
1092
16th to endDay
27%49%9%5%8%7%10%9%26%
1516
February1st to 15thDay
38%5%10%8%5%7%7%9%9%24%
1400
16th to endDay
17%5%14%12%6%7%7%8%6%21%
1504
March1st to 15thDay
8%5%10%10%6%9%7%9%9%21%
1800
16th to endDay
110%8%14%11%5%8%7%8%9%13%
2207
April1st to 15thDay
414%9%16%8%5%8%6%45%15%
2170
16th to endDay
7%15%7%14%10%45%45%6%17%
2433
May1st to 15thDay
7%18%6%11%8%44447%21%
2526
16th to endDay
17%15%6%9%7%46%45%418%
2811
June1st to 15thDay
22%13%5%10%8%35%45%5%14%
2880
16th to endDay
16%12%5%12%8%5%6%6%5%6%15%
2880
July1st to 15thDay
15%10%5%7%8%46%5%5%6%24%
2880
16th to endDay
12%7%49%9%5%7%6%5%6%25%
2786
August1st to 15thDay
11%8%48%7%5%6%6%7%7%26%
2520
16th to endDay
12%10%38%7%46%6%5%8%27%
2523
September1st to 15thDay
11%10%38%5%35%5%45%34%
2160
16th to endDay
11%8%37%6%45%46%7%32%
1836
October1st to 15thDay
6%11%49%9%37%6%8%8%22%
1636
16th to endDay
49%48%8%5%7%7%7%10%25%
1584
November1st to 15thDay
29%38%9%6%8%8%7%10%24%
1384
16th to endDay
28%410%8%37%7%7%11%27%
1260
December1st to 15thDay
27%5%12%10%5%8%8%8%8%23%
1203
16th to endDay
16%48%8%5%8%7%7%11%29%
1152
January1st to 15thNight
28%6%10%11%48%6%8%10%20%
2857
16th to endNight
16%39%9%6%8%7%8%11%25%
2706
February1st to 15thNight
38%410%10%5%8%8%7%9%23%
2452
16th to endNight
17%5%9%8%5%8%8%7%10%26%
1968
March1st to 15thNight
7%5%9%9%48%8%9%10%25%
2160
16th to endNight
28%6%10%8%48%7%8%11%21%
2012
April1st to 15thNight
38%7%10%8%5%8%6%7%8%26%
1778
16th to endNight
7%11%5%10%8%36%5%7%9%24%
1525
May1st to 15thNight
7%10%47%6%46%7%7%7%29%
1424
16th to endNight
13%9%47%7%46%6%5%7%27%
1298
June1st to 15thNight
15%10%5%8%6%46%6%7%7%21%
1080
16th to endNight
12%6%37%8%5%6%5%7%8%27%
1080
July1st to 15thNight
14%5%35%336%5%6%10%36%
1080
16th to endNight
6%5%37%7%37%6%6%7%37%
1378
August1st to 15thNight
11%8%35%6%35%6%6%8%34%
1440
16th to endNight
9%5%25%5%26%7%7%8%38%
1678
September1st to 15thNight
10%8%26%6%345%46%39%
1800
16th to endNight
8%6%25%5%35%6%8%9%38%
1796
October1st to 15thNight
5%11%49%8%46%5%6%9%28%
1993
16th to endNight
49%38%8%47%8%9%10%25%
2288
November1st to 15thNight
28%5%7%8%5%6%8%8%10%26%
2461
16th to endNight
28%5%9%9%5%7%6%8%12%24%
2700
December1st to 15thNight
37%5%12%9%5%7%6%8%10%24%
2754
16th to endNight
6%6%9%8%5%9%8%8%12%24%
3072

Percentage Cloud Cover SW (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
38%6%10%10%48%8%8%10%21%
1092
16th to endDay
29%410%9%5%6%8%7%10%24%
1516
February1st to 15thDay
39%6%13%8%37%7%8%8%23%
1400
16th to endDay
19%6%13%12%6%8%6%7%7%20%
1504
March1st to 15thDay
19%410%10%6%9%8%9%9%20%
1800
16th to endDay
211%7%15%12%5%7%6%7%9%13%
2207
April1st to 15thDay
5%17%9%14%9%47%5%5%6%14%
2170
16th to endDay
9%17%7%13%8%45%5%5%5%17%
2433
May1st to 15thDay
9%17%7%10%8%35%447%21%
2526
16th to endDay
18%14%6%9%7%46%445%17%
2811
June1st to 15thDay
25%12%5%8%8%36%5%45%14%
2880
16th to endDay
17%11%6%10%8%46%5%5%5%17%
2880
July1st to 15thDay
16%9%48%7%46%5%46%25%
2880
16th to endDay
13%8%49%9%46%6%6%6%24%
2786
August1st to 15thDay
13%7%48%7%46%6%6%7%26%
2520
16th to endDay
14%9%38%6%45%5%6%7%28%
2523
September1st to 15thDay
13%10%37%6%35%35%5%34%
2160
16th to endDay
13%9%37%6%4445%7%32%
1836
October1st to 15thDay
8%12%410%8%45%6%8%7%22%
1636
16th to endDay
5%10%48%9%48%6%7%9%24%
1584
November1st to 15thDay
210%5%10%8%5%6%7%8%9%24%
1384
16th to endDay
210%410%8%37%6%7%11%26%
1260
December1st to 15thDay
38%5%14%10%5%8%6%8%6%22%
1203
16th to endDay
16%5%9%9%5%8%7%6%11%27%
1152
January1st to 15thNight
310%6%12%11%5%8%6%7%8%18%
2856
16th to endNight
28%411%9%6%8%8%7%10%22%
2706
February1st to 15thNight
49%5%10%11%6%7%7%6%9%20%
2452
16th to endNight
17%5%9%9%5%9%8%8%9%24%
1968
March1st to 15thNight
8%5%9%10%49%8%8%10%23%
2160
16th to endNight
29%6%10%8%5%8%7%8%10%22%
2016
April1st to 15thNight
210%7%10%8%5%6%6%7%7%26%
1778
16th to endNight
8%11%5%9%8%36%5%5%9%25%
1525
May1st to 15thNight
7%11%48%7%35%7%6%8%30%
1424
16th to endNight
15%10%46%5%36%46%8%28%
1298
June1st to 15thNight
16%10%6%7%7%36%5%8%8%20%
1080
16th to endNight
14%6%37%6%47%5%6%7%29%
1080
July1st to 15thNight
15%5%24435%6%5%10%36%
1080
16th to endNight
8%5%26%7%45%7%7%7%36%
1378
August1st to 15thNight
12%8%25%5%45%6%6%9%34%
1440
16th to endNight
11%5%245%36%7%7%9%37%
1678
September1st to 15thNight
12%8%26%6%345%5%6%39%
1800
16th to endNight
9%7%245%35%6%8%9%36%
1796
October1st to 15thNight
6%12%49%8%37%6%5%8%27%
1993
16th to endNight
5%10%5%7%8%46%8%8%9%23%
2288
November1st to 15thNight
39%5%8%8%5%8%7%8%9%24%
2461
16th to endNight
210%5%10%9%5%6%7%8%10%22%
2700
December1st to 15thNight
39%7%13%9%46%6%8%9%21%
2754
16th to endNight
8%7%10%9%6%8%7%9%10%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
54%14%18%7%3
1092
16th to endDay
51%12%13%12%7%2
1516
February1st to 15thDay
53%9%14%14%6%1
1400
16th to endDay
60%7%13%12%6%
1504
March1st to 15thDay
56%11%15%12%3
1800
16th to endDay
64%10%14%7%2
2207
April1st to 15thDay
70%6%11%9%1
2170
16th to endDay
68%8%12%8%2
2433
May1st to 15thDay
63%6%13%11%5%
2526
16th to endDay
69%6%11%9%3
2816
June1st to 15thDay
72%6%10%8%2
2880
16th to endDay
67%7%12%9%3
2880
July1st to 15thDay
59%7%11%15%5%
2711
16th to endDay
59%7%15%14%3
2615
August1st to 15thDay
55%8%17%13%4
2503
16th to endDay
54%7%13%19%4
2523
September1st to 15thDay
52%5%15%19%6%1
2160
16th to endDay
50%7%16%16%6%1
1836
October1st to 15thDay
56%9%15%15%3
1636
16th to endDay
53%10%17%16%1
1584
November1st to 15thDay
53%12%17%14%2
1384
16th to endDay
50%11%20%10%5%1
1260
December1st to 15thDay
60%10%10%14%3
1203
16th to endDay
48%9%21%13%6%
1152
January1st to 15thNight
60%11%16%7%21
2857
16th to endNight
54%10%14%12%5%2
2706
February1st to 15thNight
57%9%16%10%5%1
2464
16th to endNight
51%7%15%19%5%1
1968
March1st to 15thNight
51%9%18%14%4
2160
16th to endNight
52%9%19%14%2
2016
April1st to 15thNight
54%9%16%15%3
1778
16th to endNight
56%9%16%13%3
1525
May1st to 15thNight
49%10%18%14%6%
1425
16th to endNight
54%10%16%15%3
1298
June1st to 15thNight
60%8%17%11%3
1080
16th to endNight
51%8%19%15%5%
1080
July1st to 15thNight
44%6%22%20%6%
1020
16th to endNight
42%8%22%20%4
1286
August1st to 15thNight
45%8%23%18%3
1432
16th to endNight
39%8%23%21%6%
1678
September1st to 15thNight
45%5%18%21%8%1
1800
16th to endNight
39%10%22%20%6%
1796
October1st to 15thNight
53%9%15%17%3
1993
16th to endNight
52%11%19%14%2
2288
November1st to 15thNight
51%10%20%11%4
2461
16th to endNight
53%13%15%11%41
2700
December1st to 15thNight
55%9%15%14%3
2754
16th to endNight
53%10%16%13%4
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
5%28%50%8%8%
60
16th to endDay
6%6%42%32%7%4
64
February1st to 15thDay
13%15%53%10%8%
60
16th to endDay
10%17%43%17%10%
222
March1st to 15thDay
15%32%34%11%4
270
16th to endDay
17%23%38%17%2
288
April1st to 15thDay
20%22%34%18%3
269
16th to endDay
20%25%29%16%7%
270
May1st to 15thDay
18%18%34%20%6%1
303
16th to endDay
24%10%22%24%15%2
526
June1st to 15thDay
31%12%26%20%8%
675
16th to endDay
24%14%30%22%8%
675
July1st to 15thDay
21%12%31%23%8%1
645
16th to endDay
19%12%32%25%9%
454
August1st to 15thDay
17%8%31%26%11%3
315
16th to endDay
21%17%36%17%6%
332
September1st to 15thDay
26%16%27%21%41
315
16th to endDay
24%24%29%16%4
256
October1st to 15thDay
20%20%36%16%5%
222
16th to endDay
5%13%27%36%14%3
96
November1st to 15thDay
20%13%52%8%21
67
16th to endDay
6%6%30%31%13%11%
60
December1st to 15thDay
6%18%23%20%21%10%
60
16th to endDay
114%35%28%15%4
64
January1st to 15thNight
11%17%45%19%41
922
16th to endNight
9%20%45%16%7%
771
February1st to 15thNight
11%16%41%22%8%
704
16th to endNight
7%8%44%28%9%
632
March1st to 15thNight
6%17%50%18%5%
720
16th to endNight
8%12%39%31%7%
768
April1st to 15thNight
8%14%33%30%11%
698
16th to endNight
15%10%35%29%8%
445
May1st to 15thNight
14%5%26%38%15%
360
16th to endNight
19%6%26%28%19%
375
June1st to 15thNight
23%323%31%16%
360
16th to endNight
17%7%26%30%16%
360
July1st to 15thNight
17%5%21%36%17%
340
16th to endNight
11%5%22%40%20%
376
August1st to 15thNight
15%412%36%29%1
360
16th to endNight
16%7%28%35%11%
532
September1st to 15thNight
18%6%25%29%19%1
720
16th to endNight
16%11%34%26%11%
656
October1st to 15thNight
13%13%36%29%7%
660
16th to endNight
12%15%44%20%5%
704
November1st to 15thNight
11%20%48%15%4
750
16th to endNight
10%16%48%18%41
900
December1st to 15thNight
10%15%46%20%7%
909
16th to endNight
6%14%48%20%8%1
992
Page generated at 2017-09-16 15:06:58. Version ac04

Copyright 2017 A. Danko


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