Sunrise Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sunrise Point clear sky chart from 2005-11-05 to 2017-04-26.

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
35%
14188
10%
45512
9%
14160
37%
14160
14%
34343

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
27%
720
10%
2506
8%
716
31%
716
9%
2011
January16th to endNight
32%
768
10%
2661
9%
768
35%
768
11%
2075
February1st to 15thNight
27%
697
6%
2288
4%
697
30%
697
8%
1900
February16th to endNight
25%
632
9%
1987
6%
632
28%
632
9%
1633
March1st to 15thNight
22%
720
5%
2091
4%
720
24%
720
8%
1803
March16th to endNight
21%
768
4%
2049
3%
768
22%
768
7%
1808
April1st to 15thNight
24%
719
4%
1799
2%
719
25%
719
9%
1559
April16th to endNight
31%
574
8%
1630
6%
574
32%
574
12%
1327
May1st to 15thNight
42%
329
13%
1319
16%
329
45%
329
14%
923
May16th to endNight
40%
342
4%
1368
6%
342
40%
342
9%
1083
June1st to 15thNight
37%
330
5%
1320
6%
330
39%
330
13%
954
June16th to endNight
43%
330
8%
1200
9%
330
44%
330
18%
794
July1st to 15thNight
66%
310
15%
1210
19%
310
69%
310
32%
616
July16th to endNight
70%
348
20%
1304
32%
326
75%
326
42%
574
August1st to 15thNight
74%
399
25%
1382
29%
397
76%
397
44%
647
August16th to endNight
62%
614
24%
1664
15%
614
65%
614
42%
939
September1st to 15thNight
64%
660
25%
1650
15%
660
65%
660
46%
969
September16th to endNight
49%
656
20%
1798
17%
656
51%
656
27%
1200
October1st to 15thNight
38%
660
13%
1980
12%
660
41%
660
19%
1427
October16th to endNight
35%
704
10%
2189
9%
704
37%
704
13%
1690
November1st to 15thNight
20%
700
6%
2389
4%
700
24%
700
8%
2005
November16th to endNight
28%
720
6%
2520
6%
720
29%
720
8%
2045
December1st to 15thNight
27%
720
6%
2520
6%
720
28%
720
9%
2047
December16th to endNight
16%
768
5%
2688
4%
768
18%
768
5%
2314

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%17%6%8%5%34445%28%
46157
Night
8%15%7%10%7%35%445%27%
45680
Cloud CoverDay
7%12%5%8%7%35%5%5%7%30%
46157
Night
410%5%9%8%46%6%6%7%29%
45684
TransparencyDay
54%8%10%14%9%2
45828
Night
54%9%10%13%9%2
45513
SeeingDay
21%24%28%18%5%1
5084
Night
15%18%25%23%14%2
14197

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
9%20%9%10%7%34435%20%
1432
16th to endDay
9%20%9%11%5%3445%422%
1560
February1st to 15thDay
8%18%10%13%7%37%5%46%14%
1576
16th to endDay
8%22%10%15%8%4433315%
1487
March1st to 15thDay
7%28%11%13%6%36%5%3310%
1868
16th to endDay
9%32%12%11%8%343237%
2175
April1st to 15thDay
11%27%9%10%6%3433414%
2149
16th to endDay
9%24%8%10%7%33435%18%
2239
May1st to 15thDay
11%20%47%435%446%26%
2301
16th to endDay
19%21%48%6%35%45%415%
2391
June1st to 15thDay
19%14%47%4345%5%5%24%
2310
16th to endDay
14%12%5%7%6%35%45%6%28%
2423
July1st to 15thDay
6%5%34424335%55%
2335
16th to endDay
7%313323345%60%
2461
August1st to 15thDay
6%41332335%8%56%
2239
16th to endDay
7%5%25%42445%7%48%
2184
September1st to 15thDay
8%6%2442334456%
1980
16th to endDay
15%12%35%42335%5%38%
1831
October1st to 15thDay
18%16%36%434445%29%
1650
16th to endDay
16%19%410%5%3433324%
1683
November1st to 15thDay
13%25%6%11%6%45%45%412%
1467
16th to endDay
10%25%8%10%7%35%33318%
1440
December1st to 15thDay
9%17%9%14%8%35%345%19%
1440
16th to endDay
7%24%10%11%7%35%43317%
1536
January1st to 15thNight
9%17%9%11%8%35%5%3421%
2506
16th to endNight
7%19%8%9%7%36%445%22%
2661
February1st to 15thNight
8%17%8%10%9%46%6%46%16%
2276
16th to endNight
6%16%9%13%8%46%5%35%20%
1987
March1st to 15thNight
6%19%11%13%9%46%5%5%414%
2091
16th to endNight
7%22%11%13%8%46%6%4411%
2045
April1st to 15thNight
7%21%10%12%8%46%435%16%
1799
16th to endNight
8%19%6%10%7%5%5%5%5%6%19%
1630
May1st to 15thNight
9%16%5%7%5%35%5%46%29%
1319
16th to endNight
13%15%6%10%7%45%45%6%18%
1368
June1st to 15thNight
14%15%49%5%44346%27%
1320
16th to endNight
9%11%47%7%45%45%7%32%
1200
July1st to 15thNight
5%324424425%59%
1290
16th to endNight
4412423335%65%
1400
August1st to 15thNight
3322312347%65%
1390
16th to endNight
5%424324345%57%
1664
September1st to 15thNight
5%414323447%58%
1650
16th to endNight
10%10%37%5%3345%5%40%
1798
October1st to 15thNight
13%15%47%5%2344433%
1980
16th to endNight
12%17%6%10%7%34445%24%
2189
November1st to 15thNight
13%21%6%11%8%46%43416%
2389
16th to endNight
6%20%8%14%8%35%43419%
2520
December1st to 15thNight
7%18%8%12%8%45%5%4420%
2520
16th to endNight
9%20%11%13%7%35%44315%
2688

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
311%8%13%11%45%5%5%7%23%
1432
16th to endDay
414%8%9%7%37%6%6%6%25%
1560
February1st to 15thDay
414%7%11%9%46%7%7%8%19%
1576
16th to endDay
416%8%13%9%5%7%446%18%
1487
March1st to 15thDay
216%9%14%9%46%7%6%7%14%
1868
16th to endDay
424%9%13%10%5%6%5%45%10%
2175
April1st to 15thDay
8%22%7%11%7%36%437%16%
2149
16th to endDay
7%21%6%9%7%45%447%22%
2239
May1st to 15thDay
8%18%46%6%35%5%5%8%26%
2301
16th to endDay
19%18%47%6%35%46%6%16%
2391
June1st to 15thDay
15%12%47%6%35%5%6%8%25%
2310
16th to endDay
11%10%47%6%46%5%5%7%30%
2423
July1st to 15thDay
5%424425%347%56%
2335
16th to endDay
5%323323446%61%
2461
August1st to 15thDay
5%41332345%8%57%
2239
16th to endDay
4415%5%35%46%7%50%
2184
September1st to 15thDay
6%5%14323346%58%
1980
16th to endDay
10%8%46%5%3435%6%40%
1831
October1st to 15thDay
11%15%37%435%45%6%31%
1650
16th to endDay
9%14%5%9%8%47%5%45%25%
1683
November1st to 15thDay
5%14%7%11%9%48%6%7%8%16%
1467
16th to endDay
5%15%8%12%8%47%5%45%21%
1440
December1st to 15thDay
411%7%13%9%6%6%5%5%7%23%
1440
16th to endDay
312%7%14%9%5%8%6%5%5%19%
1536
January1st to 15thNight
49%6%12%8%46%6%8%9%22%
2506
16th to endNight
312%6%10%8%47%6%5%7%25%
2661
February1st to 15thNight
411%7%11%7%47%7%7%9%20%
2276
16th to endNight
39%7%12%9%5%7%7%6%6%23%
1987
March1st to 15thNight
210%7%11%11%5%9%7%6%8%18%
2091
16th to endNight
313%8%12%9%6%8%7%6%6%15%
2049
April1st to 15thNight
5%15%6%10%12%5%6%5%5%8%18%
1799
16th to endNight
5%14%6%9%8%47%6%5%8%22%
1630
May1st to 15thNight
7%12%47%7%36%5%5%7%31%
1319
16th to endNight
9%12%5%9%10%46%5%7%8%20%
1368
June1st to 15thNight
10%12%5%7%6%45%6%6%7%27%
1320
16th to endNight
7%7%36%7%48%5%6%8%34%
1200
July1st to 15thNight
3313425%446%60%
1290
16th to endNight
2213314346%64%
1400
August1st to 15thNight
221322345%8%63%
1390
16th to endNight
2325%33445%7%57%
1664
September1st to 15thNight
431341345%7%59%
1650
16th to endNight
7%6%27%5%346%6%6%42%
1798
October1st to 15thNight
8%10%39%6%35%5%5%5%36%
1980
16th to endNight
6%10%410%8%46%6%7%7%27%
2189
November1st to 15thNight
5%14%6%10%9%5%8%6%6%7%18%
2389
16th to endNight
211%5%12%12%6%7%5%5%6%23%
2520
December1st to 15thNight
312%7%11%9%5%8%6%6%6%22%
2520
16th to endNight
5%14%7%13%10%5%6%6%6%8%16%
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
64%8%7%9%7%1
1432
16th to endDay
61%7%8%10%8%4
1560
February1st to 15thDay
66%9%8%10%31
1576
16th to endDay
71%7%6%9%4
1487
March1st to 15thDay
73%10%6%6%2
1868
16th to endDay
79%7%6%5%
2175
April1st to 15thDay
70%9%10%8%1
2149
16th to endDay
65%9%11%8%3
2239
May1st to 15thDay
54%8%12%17%6%
2301
16th to endDay
66%11%11%9%2
2395
June1st to 15thDay
54%10%16%10%5%1
2310
16th to endDay
49%10%15%16%6%1
2423
July1st to 15thDay
29%7%11%24%20%5%
2186
16th to endDay
22%7%12%24%25%8%
2294
August1st to 15thDay
22%7%15%32%17%4
2222
16th to endDay
30%9%13%27%17%2
2184
September1st to 15thDay
27%5%11%24%25%4
1980
16th to endDay
44%7%12%18%12%4
1831
October1st to 15thDay
53%6%10%19%10%1
1650
16th to endDay
62%5%7%14%8%
1683
November1st to 15thDay
70%10%7%8%21
1467
16th to endDay
68%6%5%8%8%2
1440
December1st to 15thDay
66%9%7%9%6%
1440
16th to endDay
69%8%8%8%5%
1536
January1st to 15thNight
62%9%7%9%8%2
2506
16th to endNight
61%7%8%9%7%6%
2661
February1st to 15thNight
64%11%8%9%41
2288
16th to endNight
64%8%8%11%5%
1987
March1st to 15thNight
66%12%8%9%3
2091
16th to endNight
68%12%8%7%1
2049
April1st to 15thNight
67%10%10%8%2
1799
16th to endNight
59%11%11%12%3
1630
May1st to 15thNight
50%9%12%17%8%
1320
16th to endNight
59%12%15%9%3
1368
June1st to 15thNight
52%9%15%15%6%
1320
16th to endNight
42%11%18%19%6%1
1200
July1st to 15thNight
24%10%12%25%20%7%
1210
16th to endNight
18%6%12%23%27%11%
1304
August1st to 15thNight
17%8%14%30%24%5%
1382
16th to endNight
24%7%15%29%20%2
1664
September1st to 15thNight
22%8%12%24%24%6%
1650
16th to endNight
39%8%13%17%13%7%
1798
October1st to 15thNight
50%7%9%19%11%1
1980
16th to endNight
58%7%8%14%9%1
2189
November1st to 15thNight
67%8%9%9%21
2389
16th to endNight
65%8%5%8%9%2
2520
December1st to 15thNight
64%8%9%10%6%
2520
16th to endNight
69%10%7%6%4
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
11%16%26%21%20%3
60
16th to endDay
21%32%21%11%11%1
88
February1st to 15thDay
25%30%26%12%4
236
16th to endDay
24%33%21%15%4
223
March1st to 15thDay
27%43%20%7%
270
16th to endDay
33%35%20%9%1
288
April1st to 15thDay
26%31%23%11%42
269
16th to endDay
29%31%20%12%32
254
May1st to 15thDay
27%21%30%16%21
228
16th to endDay
31%16%24%21%41
266
June1st to 15thDay
22%26%23%19%7%1
255
16th to endDay
21%22%33%15%6%
368
July1st to 15thDay
10%15%36%30%5%
270
16th to endDay
5%17%38%26%8%3
271
August1st to 15thDay
9%11%38%29%7%4
255
16th to endDay
7%15%34%27%9%5%
268
September1st to 15thDay
16%16%29%25%10%2
255
16th to endDay
18%18%29%27%6%
255
October1st to 15thDay
25%26%24%17%5%
255
16th to endDay
30%18%29%15%42
195
November1st to 15thDay
19%30%36%12%
71
16th to endDay
25%26%21%11%13%1
60
December1st to 15thDay
28%40%26%5%
60
16th to endDay
17%21%35%14%9%1
64
January1st to 15thNight
19%26%22%20%10%1
720
16th to endNight
15%21%25%23%10%3
768
February1st to 15thNight
17%19%28%23%9%
704
16th to endNight
17%21%28%23%7%
632
March1st to 15thNight
15%27%28%19%7%
720
16th to endNight
16%27%30%17%6%1
768
April1st to 15thNight
16%21%30%21%8%2
719
16th to endNight
13%19%29%22%11%2
574
May1st to 15thNight
14%17%20%27%16%3
330
16th to endNight
14%12%23%29%19%
343
June1st to 15thNight
15%13%28%27%14%
330
16th to endNight
12%11%28%29%18%
330
July1st to 15thNight
4322%38%29%1
310
16th to endNight
26%17%39%30%3
348
August1st to 15thNight
4314%35%36%6%
399
16th to endNight
6%5%21%30%28%7%
614
September1st to 15thNight
7%5%18%28%30%8%
660
16th to endNight
13%11%21%28%21%4
656
October1st to 15thNight
18%13%25%23%16%3
660
16th to endNight
19%18%22%24%11%3
704
November1st to 15thNight
22%22%31%19%4
700
16th to endNight
18%26%21%19%12%1
720
December1st to 15thNight
16%22%29%21%8%1
720
16th to endNight
18%28%34%13%5%
768
Page generated at 2017-04-27 14:48:46. Version ac04

Copyright 2017 A. Danko


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