Hope
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hope clear sky chart from 2005-11-06 to 2024-01-31.

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
26%
22513
8%
75001
6%
22453
29%
22453
11%
59008

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 10thNight
11%
850
7%
2836
3%
846
17%
846
6%
2436
January11th to 20thNight
15%
801
8%
2747
4%
801
21%
801
8%
2247
January21st to endNight
17%
834
8%
2918
4%
834
22%
834
8%
2383
February1st to 10thNight
11%
720
6%
2390
2%
720
16%
720
7%
2009
February11th to 20thNight
13%
701
7%
2274
3%
700
19%
700
7%
1915
February21st to endNight
17%
592
10%
1855
5%
592
25%
592
8%
1523
March1st to 10thNight
22%
720
7%
2160
5%
720
25%
720
10%
1767
March11th to 20thNight
20%
720
8%
1991
4%
720
23%
720
9%
1670
March21st to endNight
17%
792
4%
2070
1%
792
19%
792
8%
1814
April1st to 10thNight
21%
720
4%
1800
2%
720
22%
720
10%
1551
April11th to 20thNight
22%
689
8%
1757
3%
689
25%
689
11%
1465
April21st to endNight
22%
423
5%
1503
3%
423
25%
423
7%
1259
May1st to 10thNight
34%
360
8%
1440
10%
360
36%
360
9%
1113
May11th to 20thNight
41%
354
7%
1416
10%
354
43%
354
10%
1056
May21st to endNight
36%
389
4%
1552
7%
388
37%
388
10%
1184
June1st to 10thNight
32%
360
3%
1305
2%
360
32%
360
11%
1024
June11th to 20thNight
32%
360
1%
1260
0%
360
32%
360
7%
1066
June21st to endNight
46%
360
5%
1260
1%
360
47%
360
18%
863
July1st to 10thNight
55%
350
5%
1225
4%
350
55%
350
22%
787
July11th to 20thNight
56%
348
10%
1256
11%
348
58%
348
26%
745
July21st to endNight
70%
394
15%
1488
26%
372
73%
372
36%
712
August1st to 10thNight
67%
358
15%
1424
22%
356
69%
356
29%
752
August11th to 20thNight
63%
468
20%
1536
19%
468
67%
468
35%
835
August21st to endNight
48%
702
17%
1890
12%
702
50%
702
25%
1293
September1st to 10thNight
42%
720
15%
1800
8%
720
44%
720
28%
1246
September11th to 20thNight
43%
720
18%
1800
10%
720
45%
720
24%
1312
September21st to endNight
36%
720
14%
2040
10%
720
39%
720
17%
1527
October1st to 10thNight
32%
720
8%
2160
8%
720
34%
720
15%
1610
October11th to 20thNight
28%
720
10%
2160
8%
720
31%
720
12%
1699
October21st to endNight
18%
792
8%
2551
5%
792
23%
792
9%
2051
November1st to 10thNight
10%
740
5%
2558
2%
740
14%
740
6%
2181
November11th to 20thNight
12%
760
7%
2660
3%
760
17%
760
7%
2212
November21st to endNight
12%
760
5%
2660
2%
760
16%
760
7%
2221
December1st to 10thNight
18%
760
9%
2660
4%
760
24%
760
9%
2098
December11th to 20thNight
10%
802
4%
3403
2%
801
13%
801
4%
2957
December21st to endNight
6%
934
4%
5196
1%
905
11%
905
3%
4425

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
22%16%47%5%34445%27%
74936
Night
23%17%47%5%34445%25%
75201
TransparencyDay
60%7%10%14%7%1
74627
Night
62%7%10%12%7%1
75028
SeeingDay
30%18%26%19%6%1
13992
Night
33%12%24%22%9%
22517

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 10thDay
29%22%48%5%3333315%
1329
11th to 20thDay
24%18%6%9%7%32445%20%
1430
21st to endDay
23%23%5%7%423345%21%
1664
February1st to 10thDay
27%21%6%9%5%23335%16%
1570
11th to 20thDay
19%28%47%5%3344418%
1575
21st to endDay
15%27%6%8%7%45%43316%
1400
March1st to 10thDay
19%24%7%10%7%3344416%
1800
11th to 20thDay
20%28%6%8%6%3334416%
1966
21st to endDay
22%25%6%9%6%34345%13%
2286
April1st to 10thDay
21%29%5%8%6%2435%5%12%
2160
11th to 20thDay
21%24%6%8%6%35%445%16%
2152
21st to endDay
26%23%5%7%5%3435%5%16%
2456
May1st to 10thDay
21%20%47%5%34445%23%
2520
11th to 20thDay
20%13%47%6%446%5%7%24%
2477
21st to endDay
32%12%47%5%34345%22%
2723
June1st to 10thDay
31%11%48%6%3434421%
2653
11th to 20thDay
39%13%5%7%5%2344415%
2700
21st to endDay
24%8%36%5%33446%32%
2700
July1st to 10thDay
16%8%35%424445%43%
2700
11th to 20thDay
15%6%34434447%46%
2660
21st to endDay
11%5%2332335%5%57%
2741
August1st to 10thDay
15%5%2442435%6%51%
2507
11th to 20thDay
11%5%2442445%6%54%
2361
21st to endDay
18%8%36%5%345%5%6%38%
2465
September1st to 10thDay
16%7%36%433446%44%
2160
11th to 20thDay
21%9%37%5%3434437%
2160
21st to endDay
25%11%35%424346%33%
1917
October1st to 10thDay
24%11%36%5%3445%6%30%
1800
11th to 20thDay
26%12%48%5%34345%26%
1800
21st to endDay
32%14%37%424445%22%
1805
November1st to 10thDay
32%20%46%5%3344416%
1516
11th to 20thDay
30%24%37%33222321%
1520
21st to endDay
27%20%5%7%5%3333419%
1520
December1st to 10thDay
22%20%5%6%5%2443325%
1520
11th to 20thDay
20%23%6%10%6%3333418%
1781
21st to endDay
19%24%7%10%8%45%44411%
2442
January1st to 10thNight
29%22%7%7%5%3333415%
2836
11th to 20thNight
26%18%5%7%5%24347%18%
2747
21st to endNight
21%22%5%8%5%33445%19%
2918
February1st to 10thNight
26%20%7%7%5%24335%17%
2390
11th to 20thNight
21%27%5%7%43433319%
2272
21st to endNight
19%23%6%8%6%2445%5%18%
1855
March1st to 10thNight
21%20%6%6%5%34446%21%
2160
11th to 20thNight
21%26%5%6%6%2335%419%
1990
21st to endNight
22%23%5%8%6%3444417%
2070
April1st to 10thNight
16%26%5%9%7%34345%18%
1800
11th to 20thNight
21%23%48%6%34435%20%
1757
21st to endNight
25%21%5%7%43445%417%
1503
May1st to 10thNight
22%16%36%6%35%445%27%
1440
11th to 20thNight
19%13%35%5%46%6%5%6%28%
1416
21st to endNight
28%11%26%5%3445%7%26%
1552
June1st to 10thNight
28%10%46%5%3446%5%24%
1305
11th to 20thNight
31%11%47%6%3445%6%19%
1260
21st to endNight
21%8%25%43345%7%37%
1260
July1st to 10thNight
16%8%35%43335%5%45%
1260
11th to 20thNight
13%6%235%24446%50%
1298
21st to endNight
10%31332435%6%59%
1576
August1st to 10thNight
12%413334346%57%
1432
11th to 20thNight
10%5%1332335%7%57%
1536
21st to endNight
14%7%35%5%445%6%8%39%
1890
September1st to 10thNight
16%8%36%5%33345%45%
1800
11th to 20thNight
23%8%36%423335%39%
1800
21st to endNight
24%10%36%6%2435%6%32%
2040
October1st to 10thNight
22%11%36%5%34445%31%
2160
11th to 20thNight
30%13%45%5%3433427%
2160
21st to endNight
31%16%36%5%3433423%
2551
November1st to 10thNight
34%17%5%7%43443416%
2558
11th to 20thNight
31%21%46%5%3333418%
2660
21st to endNight
27%24%5%7%43334318%
2660
December1st to 10thNight
21%18%5%7%5%24445%25%
2660
11th to 20thNight
26%21%6%10%6%3443413%
3415
21st to endNight
19%26%7%9%6%34445%12%
5214

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 10thDay
76%46%9%41
1329
11th to 20thDay
69%6%8%10%43
1430
21st to endDay
67%5%7%13%8%
1664
February1st to 10thDay
73%5%7%8%5%1
1570
11th to 20thDay
70%6%8%9%6%1
1584
21st to endDay
72%6%7%10%31
1400
March1st to 10thDay
72%7%7%9%41
1800
11th to 20thDay
73%6%8%9%3
1966
21st to endDay
76%6%10%7%1
2286
April1st to 10thDay
76%8%9%7%1
2160
11th to 20thDay
71%8%6%8%7%1
2152
21st to endDay
72%7%8%7%5%
2456
May1st to 10thDay
63%8%11%13%4
2520
11th to 20thDay
59%9%14%14%3
2480
21st to endDay
66%8%12%13%2
2724
June1st to 10thDay
67%7%11%10%33
2653
11th to 20thDay
74%7%9%8%2
2700
21st to endDay
54%8%14%17%6%1
2700
July1st to 10thDay
44%8%11%23%11%3
2626
11th to 20thDay
38%8%15%24%13%2
2579
21st to endDay
26%6%14%30%18%5%
2589
August1st to 10thDay
34%8%17%22%16%3
2490
11th to 20thDay
31%9%17%24%17%3
2361
21st to endDay
45%7%16%23%7%2
2465
September1st to 10thDay
41%8%13%22%12%4
2160
11th to 20thDay
51%6%8%16%16%3
2160
21st to endDay
53%7%13%16%9%2
1917
October1st to 10thDay
56%7%12%17%9%
1800
11th to 20thDay
61%7%9%15%7%1
1800
21st to endDay
65%5%10%12%7%
1805
November1st to 10thDay
73%6%8%8%41
1516
11th to 20thDay
72%47%9%5%2
1520
21st to endDay
69%7%5%10%7%2
1520
December1st to 10thDay
65%8%8%10%8%1
1520
11th to 20thDay
68%10%7%10%41
1783
21st to endDay
75%7%9%6%3
2442
January1st to 10thNight
75%5%5%11%32
2836
11th to 20thNight
67%7%8%10%5%2
2747
21st to endNight
67%7%8%9%8%1
2918
February1st to 10thNight
71%6%8%10%5%1
2390
11th to 20thNight
71%6%7%9%5%2
2274
21st to endNight
67%7%8%14%4
1855
March1st to 10thNight
65%8%11%10%6%1
2160
11th to 20thNight
69%6%9%12%4
1991
21st to endNight
71%9%12%7%1
2070
April1st to 10thNight
70%7%12%9%2
1800
11th to 20thNight
66%7%10%10%7%1
1757
21st to endNight
70%7%9%9%5%1
1503
May1st to 10thNight
60%9%12%13%41
1440
11th to 20thNight
56%11%17%12%5%
1416
21st to endNight
59%9%15%15%2
1552
June1st to 10thNight
61%9%14%11%32
1305
11th to 20thNight
64%13%11%9%2
1260
21st to endNight
47%9%19%18%6%1
1260
July1st to 10thNight
43%7%16%19%14%1
1225
11th to 20thNight
36%8%18%26%11%2
1256
21st to endNight
23%8%16%29%21%4
1488
August1st to 10thNight
29%8%18%24%19%2
1424
11th to 20thNight
27%8%23%22%18%3
1536
21st to endNight
41%10%16%23%9%2
1890
September1st to 10thNight
42%7%14%20%15%3
1800
11th to 20thNight
49%5%9%16%16%4
1800
21st to endNight
53%8%13%15%9%2
2040
October1st to 10thNight
55%7%12%18%8%
2160
11th to 20thNight
62%6%9%13%9%1
2160
21st to endNight
66%5%8%12%8%
2551
November1st to 10thNight
72%7%8%8%41
2558
11th to 20thNight
70%6%8%8%6%2
2660
21st to endNight
72%5%5%8%8%2
2660
December1st to 10thNight
63%7%10%12%7%1
2660
11th to 20thNight
74%8%8%7%31
3412
21st to endNight
72%9%7%7%4
5214

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 10thDay
32%27%19%16%6%1
180
11th to 20thDay
33%18%26%17%6%1
180
21st to endDay
32%17%29%17%6%
196
February1st to 10thDay
46%21%18%14%1
290
11th to 20thDay
40%19%24%14%31
335
21st to endDay
32%22%29%14%4
311
March1st to 10thDay
31%23%28%14%4
420
11th to 20thDay
34%21%19%18%7%
420
21st to endDay
37%21%21%15%5%
462
April1st to 10thDay
41%19%20%16%4
420
11th to 20thDay
33%22%23%15%7%
412
21st to endDay
39%21%21%14%5%1
420
May1st to 10thDay
28%16%33%19%4
423
11th to 20thDay
28%14%27%23%7%2
448
21st to endDay
35%15%24%18%6%2
485
June1st to 10thDay
31%23%24%17%5%
583
11th to 20thDay
40%20%25%11%3
630
21st to endDay
27%16%27%22%7%2
630
July1st to 10thDay
23%15%34%23%6%1
621
11th to 20thDay
18%19%37%20%6%1
578
21st to endDay
13%12%36%26%11%2
487
August1st to 10thDay
17%11%31%28%11%2
447
11th to 20thDay
11%12%33%32%10%3
437
21st to endDay
20%19%30%21%9%1
495
September1st to 10thDay
21%20%31%21%6%1
450
11th to 20thDay
29%14%26%21%9%
450
21st to endDay
31%16%24%20%8%1
450
October1st to 10thDay
29%17%22%21%10%1
450
11th to 20thDay
36%16%19%19%9%1
450
21st to endDay
41%15%23%16%5%
320
November1st to 10thDay
40%12%26%18%4
194
11th to 20thDay
42%15%20%13%10%1
180
21st to endDay
39%25%17%9%10%1
180
December1st to 10thDay
41%13%19%20%6%1
180
11th to 20thDay
41%16%23%16%22
180
21st to endDay
33%22%30%14%1
198
January1st to 10thNight
43%20%22%13%2
850
11th to 20thNight
36%16%29%17%3
801
21st to endNight
35%16%29%20%1
834
February1st to 10thNight
38%17%29%13%2
720
11th to 20thNight
37%16%27%17%2
704
21st to endNight
33%15%29%18%4
592
March1st to 10thNight
33%14%25%21%7%
720
11th to 20thNight
38%16%22%19%5%
720
21st to endNight
36%14%26%18%6%
792
April1st to 10thNight
33%13%22%25%6%1
720
11th to 20thNight
33%16%23%23%5%
689
21st to endNight
37%12%22%22%8%
423
May1st to 10thNight
29%11%20%28%13%
360
11th to 20thNight
29%8%16%31%17%
354
21st to endNight
32%7%19%28%14%1
389
June1st to 10thNight
32%7%23%25%12%1
360
11th to 20thNight
34%11%16%26%12%
360
21st to endNight
23%6%18%34%19%1
360
July1st to 10thNight
18%5%17%36%24%1
350
11th to 20thNight
15%7%18%38%22%1
348
21st to endNight
10%414%40%31%1
394
August1st to 10thNight
12%312%34%35%3
358
11th to 20thNight
12%316%38%29%2
468
21st to endNight
19%6%21%33%21%
702
September1st to 10thNight
22%7%26%27%18%
720
11th to 20thNight
26%9%16%27%20%2
720
21st to endNight
31%8%20%30%10%
720
October1st to 10thNight
28%9%24%29%9%
720
11th to 20thNight
39%10%18%26%6%
720
21st to endNight
42%12%24%17%4
792
November1st to 10thNight
46%13%29%12%1
740
11th to 20thNight
45%15%25%13%2
760
21st to endNight
44%17%22%14%3
760
December1st to 10thNight
31%15%33%18%3
760
11th to 20thNight
42%17%27%12%2
802
21st to endNight
39%18%33%10%1
935
Page generated at 2024-01-28 02:26:34. Version ac07

Copyright 2024 Attilla Danko


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