Riverbend Recreation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Riverbend Recreation Area clear sky chart from 2005-11-06 to 2024-01-27.

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
36%
24266
16%
74659
10%
24212
42%
24212
20%
52124

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
16%
949
12%
2648
4%
946
24%
946
12%
2097
January11th to 20thNight
15%
865
8%
2575
3%
865
19%
865
10%
2095
January21st to endNight
17%
820
11%
2664
6%
820
24%
820
10%
2105
February1st to 10thNight
17%
720
8%
2340
5%
720
21%
720
11%
1842
February11th to 20thNight
20%
700
13%
2103
7%
700
26%
700
13%
1583
February21st to endNight
16%
592
13%
1776
3%
592
25%
592
13%
1353
March1st to 10thNight
26%
720
14%
2118
8%
720
32%
720
17%
1542
March11th to 20thNight
29%
720
20%
1980
9%
720
39%
720
23%
1350
March21st to endNight
29%
792
17%
2178
9%
792
36%
792
19%
1579
April1st to 10thNight
26%
631
15%
1891
6%
631
35%
631
20%
1313
April11th to 20thNight
30%
533
20%
1656
9%
533
39%
533
21%
1105
April21st to endNight
31%
540
17%
1620
5%
540
40%
540
22%
1119
May1st to 10thNight
36%
540
11%
1620
6%
540
40%
540
17%
1194
May11th to 20thNight
38%
531
16%
1593
9%
531
45%
531
24%
1073
May21st to endNight
56%
583
15%
1745
11%
582
60%
582
32%
1058
June1st to 10thNight
54%
540
15%
1555
12%
540
57%
540
32%
967
June11th to 20thNight
57%
540
18%
1440
13%
540
62%
540
34%
920
June21st to endNight
56%
540
19%
1440
14%
540
61%
540
34%
901
July1st to 10thNight
65%
525
16%
1400
15%
525
66%
525
35%
895
July11th to 20thNight
67%
522
20%
1431
17%
522
70%
522
39%
845
July21st to endNight
66%
591
19%
1672
16%
558
69%
558
35%
998
August1st to 10thNight
68%
537
21%
1600
19%
534
69%
534
35%
938
August11th to 20thNight
66%
534
21%
1598
17%
534
69%
534
34%
955
August21st to endNight
68%
594
21%
1844
18%
594
70%
594
34%
1071
September1st to 10thNight
59%
654
22%
1914
17%
654
63%
654
33%
1156
September11th to 20thNight
63%
720
29%
1980
22%
720
66%
720
38%
1171
September21st to endNight
51%
720
24%
1980
18%
720
57%
720
32%
1257
October1st to 10thNight
50%
720
21%
2009
16%
720
55%
720
30%
1260
October11th to 20thNight
33%
720
19%
2160
12%
720
41%
720
22%
1444
October21st to endNight
29%
792
19%
2493
13%
792
37%
792
19%
1726
November1st to 10thNight
36%
740
21%
2406
16%
740
45%
740
25%
1501
November11th to 20thNight
28%
760
20%
2470
12%
760
39%
760
19%
1669
November21st to endNight
25%
760
15%
2470
10%
760
32%
760
14%
1841
December1st to 10thNight
18%
760
10%
2470
5%
760
24%
760
11%
1919
December11th to 20thNight
18%
759
10%
3015
4%
759
26%
759
10%
2212
December21st to endNight
16%
1002
4%
4805
3%
988
21%
988
5%
4070

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
15%9%47%6%45%5%5%7%33%
75152
Night
16%9%47%6%3445%7%35%
74896
TransparencyDay
49%7%12%19%11%2
74865
Night
49%6%12%20%12%2
74703
SeeingDay
18%10%27%23%15%7%
14378
Night
20%9%27%29%13%1
24277

By Month

Percentage Cloud Cover SE (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
18%15%6%11%9%5%5%445%18%
1517
11th to 20thDay
17%19%8%12%8%45%43416%
1600
21st to endDay
18%16%9%9%9%45%35%5%17%
1836
February1st to 10thDay
19%15%6%10%8%5%5%435%21%
1620
11th to 20thDay
15%13%6%12%9%45%5%45%22%
1741
21st to endDay
18%14%6%9%5%3445%7%26%
1480
March1st to 10thDay
19%13%6%9%8%45%35%5%25%
1841
11th to 20thDay
18%12%5%8%5%3445%7%29%
1980
21st to endDay
24%12%5%9%6%34446%24%
2178
April1st to 10thDay
14%11%5%8%7%45%5%5%6%31%
2083
11th to 20thDay
18%8%36%6%45%46%7%34%
2253
21st to endDay
21%8%36%6%34447%34%
2340
May1st to 10thDay
18%8%36%7%36%5%49%30%
2340
11th to 20thDay
20%7%36%6%4446%6%34%
2301
21st to endDay
10%6%27%7%45%5%6%8%40%
2531
June1st to 10thDay
14%5%36%6%45%5%6%8%39%
2401
11th to 20thDay
11%5%25%6%46%6%6%8%41%
2520
21st to endDay
11%5%25%6%46%6%7%10%39%
2520
July1st to 10thDay
10%5%26%6%45%6%6%10%42%
2520
11th to 20thDay
8%425%6%36%6%6%9%45%
2479
21st to endDay
8%436%6%45%6%7%10%43%
2547
August1st to 10thDay
8%425%5%45%6%6%10%45%
2327
11th to 20thDay
9%5%25%6%5%6%6%8%10%39%
2303
21st to endDay
9%5%25%5%35%5%6%9%43%
2508
September1st to 10thDay
14%5%25%5%35%46%8%44%
2026
11th to 20thDay
10%5%25%435%5%6%9%46%
1980
21st to endDay
16%6%25%6%3335%7%43%
1980
October1st to 10thDay
14%7%36%5%435%5%7%41%
1950
11th to 20thDay
17%7%36%5%35%5%5%6%38%
1800
21st to endDay
20%9%36%7%45%46%6%30%
1859
November1st to 10thDay
12%8%27%43445%7%44%
1672
11th to 20thDay
18%13%5%6%5%34445%35%
1710
21st to endDay
19%14%5%7%5%34446%29%
1710
December1st to 10thDay
16%17%9%11%7%45%43420%
1710
11th to 20thDay
16%14%6%10%7%46%5%6%6%22%
2153
21st to endDay
22%22%8%10%7%45%33411%
2836
January1st to 10thNight
17%14%6%10%7%445%4424%
2648
11th to 20thNight
18%15%7%11%7%45%445%20%
2575
21st to endNight
17%16%8%10%7%4434423%
2664
February1st to 10thNight
21%13%5%9%7%4445%5%23%
2340
11th to 20thNight
16%13%6%9%7%45%45%6%26%
2102
21st to endNight
22%13%48%7%33446%26%
1776
March1st to 10thNight
16%11%49%7%34445%33%
2118
11th to 20thNight
14%8%35%5%445%5%7%39%
1980
21st to endNight
20%9%47%5%34445%35%
2178
April1st to 10thNight
15%9%37%6%345%5%7%36%
1891
11th to 20thNight
17%7%26%5%46%5%6%7%37%
1656
21st to endNight
17%8%27%5%35%45%7%37%
1620
May1st to 10thNight
19%7%37%7%45%5%6%6%31%
1620
11th to 20thNight
20%6%35%42446%8%38%
1592
21st to endNight
10%5%24436%5%7%10%44%
1744
June1st to 10thNight
10%5%25%5%346%7%8%45%
1555
11th to 20thNight
8%5%35%445%5%6%9%46%
1440
21st to endNight
10%425%5%45%5%6%10%45%
1440
July1st to 10thNight
9%425%6%345%5%9%47%
1440
11th to 20thNight
7%424445%5%7%10%49%
1479
21st to endNight
7%425%5%35%6%7%8%49%
1771
August1st to 10thNight
7%325%5%36%5%8%10%48%
1611
11th to 20thNight
8%5%36%4345%6%8%48%
1598
21st to endNight
7%425%5%35%5%5%9%50%
1844
September1st to 10thNight
12%5%25%5%25%35%7%50%
1914
11th to 20thNight
11%424333447%54%
1980
21st to endNight
13%425%6%3445%6%47%
1980
October1st to 10thNight
12%6%25%435%45%7%48%
2009
11th to 20thNight
18%9%36%5%2435%7%38%
2160
21st to endNight
22%7%35%5%3445%5%36%
2493
November1st to 10thNight
14%8%35%5%245%5%6%44%
2406
11th to 20thNight
16%11%46%43445%7%35%
2470
21st to endNight
20%11%5%8%6%35%446%28%
2470
December1st to 10thNight
19%13%6%10%7%35%45%6%23%
2470
11th to 20thNight
18%14%6%9%5%3445%6%25%
3042
21st to endNight
26%19%7%8%6%34445%13%
4820

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
69%6%9%12%4
1518
11th to 20thDay
73%5%10%8%4
1600
21st to endDay
70%5%9%11%5%1
1836
February1st to 10thDay
67%5%9%12%6%1
1620
11th to 20thDay
64%6%8%14%7%1
1751
21st to endDay
58%6%12%15%8%2
1480
March1st to 10thDay
61%5%10%18%6%
1841
11th to 20thDay
56%5%12%17%9%2
1980
21st to endDay
61%5%9%18%5%1
2178
April1st to 10thDay
53%6%11%17%12%
2083
11th to 20thDay
49%6%12%18%12%2
2253
21st to endDay
51%5%12%20%10%2
2340
May1st to 10thDay
52%7%12%18%10%1
2340
11th to 20thDay
49%8%11%18%13%2
2305
21st to endDay
40%9%14%23%12%2
2531
June1st to 10thDay
42%7%11%24%13%2
2401
11th to 20thDay
39%8%14%22%16%2
2520
21st to endDay
38%9%16%19%14%4
2520
July1st to 10thDay
38%8%11%23%17%3
2451
11th to 20thDay
33%9%14%26%16%2
2404
21st to endDay
34%9%15%24%15%2
2405
August1st to 10thDay
33%8%15%27%16%1
2314
11th to 20thDay
36%9%16%26%11%2
2303
21st to endDay
35%7%15%22%17%4
2508
September1st to 10thDay
38%6%14%22%17%4
2026
11th to 20thDay
35%6%11%26%19%2
1980
21st to endDay
41%5%11%23%20%1
1980
October1st to 10thDay
41%7%12%24%15%2
1950
11th to 20thDay
45%7%11%21%15%2
1800
21st to endDay
54%5%12%18%10%1
1859
November1st to 10thDay
40%6%12%23%18%1
1672
11th to 20thDay
53%410%20%11%2
1710
21st to endDay
57%5%12%17%9%
1710
December1st to 10thDay
69%5%9%14%4
1710
11th to 20thDay
60%7%12%17%5%
2150
21st to endDay
78%5%7%6%3
2836
January1st to 10thNight
63%5%8%16%8%
2648
11th to 20thNight
67%5%10%13%4
2575
21st to endNight
65%410%14%6%1
2664
February1st to 10thNight
64%5%12%13%5%1
2340
11th to 20thNight
59%5%10%17%8%1
2103
21st to endNight
59%6%10%15%8%2
1776
March1st to 10thNight
54%6%11%18%10%1
2118
11th to 20thNight
44%6%11%22%14%3
1980
21st to endNight
51%6%9%23%10%1
2178
April1st to 10thNight
48%6%11%19%14%1
1891
11th to 20thNight
45%7%11%18%17%2
1656
21st to endNight
47%6%11%20%14%3
1620
May1st to 10thNight
53%7%10%15%12%2
1620
11th to 20thNight
44%7%12%18%17%2
1593
21st to endNight
33%8%16%26%15%3
1745
June1st to 10thNight
34%8%12%25%17%4
1555
11th to 20thNight
33%9%14%25%17%3
1440
21st to endNight
34%6%16%24%16%3
1440
July1st to 10thNight
35%7%12%25%18%4
1400
11th to 20thNight
28%8%16%27%20%1
1431
21st to endNight
30%8%16%25%17%4
1672
August1st to 10thNight
30%8%14%29%18%1
1600
11th to 20thNight
32%7%16%27%15%2
1598
21st to endNight
30%8%15%22%21%4
1844
September1st to 10thNight
34%6%13%24%17%5%
1914
11th to 20thNight
30%6%12%26%25%2
1980
21st to endNight
36%6%11%24%20%3
1980
October1st to 10thNight
36%6%12%23%20%1
2009
11th to 20thNight
46%5%10%23%15%1
2160
21st to endNight
49%5%10%22%11%2
2493
November1st to 10thNight
40%5%11%24%18%2
2406
11th to 20thNight
48%5%10%21%13%1
2470
21st to endNight
57%6%11%18%7%
2470
December1st to 10thNight
61%6%10%15%7%
2470
11th to 20thNight
58%5%14%16%5%1
3044
21st to endNight
74%6%10%8%3
4820

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
25%19%30%18%7%1
270
11th to 20thDay
27%17%36%14%5%1
270
21st to endDay
30%17%30%17%5%1
282
February1st to 10thDay
33%17%34%16%
240
11th to 20thDay
26%16%37%17%3
240
21st to endDay
26%20%42%11%2
198
March1st to 10thDay
26%17%35%17%5%
281
11th to 20thDay
23%15%34%20%7%2
420
21st to endDay
31%13%29%19%6%1
462
April1st to 10thDay
22%13%29%25%10%1
420
11th to 20thDay
22%16%29%19%9%5%
412
21st to endDay
27%13%29%22%8%2
420
May1st to 10thDay
25%10%31%21%10%2
423
11th to 20thDay
22%11%23%25%14%6%
447
21st to endDay
13%6%24%25%22%10%
485
June1st to 10thDay
13%6%27%31%18%6%
511
11th to 20thDay
12%5%28%26%23%5%
630
21st to endDay
13%6%28%27%19%7%
630
July1st to 10thDay
11%319%28%24%15%
621
11th to 20thDay
8%423%28%23%14%
577
21st to endDay
9%417%25%29%15%
488
August1st to 10thDay
9%414%25%27%20%
446
11th to 20thDay
10%218%29%28%12%
439
21st to endDay
8%420%25%26%17%
495
September1st to 10thDay
18%417%25%25%12%
450
11th to 20thDay
10%416%24%30%16%
450
21st to endDay
19%9%18%24%19%11%
450
October1st to 10thDay
13%9%24%26%21%7%
450
11th to 20thDay
18%17%29%25%10%2
450
21st to endDay
24%14%37%17%5%2
374
November1st to 10thDay
16%14%36%19%11%4
270
11th to 20thDay
25%19%27%21%8%
270
21st to endDay
29%14%35%19%3
270
December1st to 10thDay
21%21%33%16%8%1
270
11th to 20thDay
23%18%37%18%5%
270
21st to endDay
27%19%34%17%3
297
January1st to 10thNight
25%14%34%20%6%
950
11th to 20thNight
28%15%35%18%41
865
21st to endNight
25%14%35%21%5%
820
February1st to 10thNight
29%10%34%24%3
720
11th to 20thNight
24%13%36%24%3
703
21st to endNight
29%12%38%19%3
592
March1st to 10thNight
22%11%34%26%7%
720
11th to 20thNight
19%14%34%26%6%1
720
21st to endNight
23%10%31%27%8%1
792
April1st to 10thNight
19%15%35%26%5%1
631
11th to 20thNight
20%10%37%23%9%1
533
21st to endNight
21%8%36%26%9%
540
May1st to 10thNight
23%8%26%32%10%1
540
11th to 20thNight
24%427%30%15%1
531
21st to endNight
13%222%39%21%3
584
June1st to 10thNight
11%224%43%19%1
540
11th to 20thNight
12%223%43%19%1
540
21st to endNight
12%321%38%25%1
540
July1st to 10thNight
11%214%41%29%3
525
11th to 20thNight
9%315%40%29%4
522
21st to endNight
10%114%44%29%2
591
August1st to 10thNight
8%212%43%32%3
537
11th to 20thNight
10%213%39%31%5%
534
21st to endNight
8%312%38%34%5%
594
September1st to 10thNight
14%415%34%30%5%
654
11th to 20thNight
12%313%36%31%5%
720
21st to endNight
15%5%22%32%24%2
720
October1st to 10thNight
16%6%24%31%21%3
720
11th to 20thNight
22%13%28%27%10%1
720
21st to endNight
25%12%29%27%7%
792
November1st to 10thNight
17%10%32%26%13%1
740
11th to 20thNight
22%13%31%25%8%1
760
21st to endNight
26%11%31%25%6%1
760
December1st to 10thNight
25%14%34%23%5%
760
11th to 20thNight
25%14%34%22%4
760
21st to endNight
32%12%31%21%3
1007
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