Rogue River Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rogue River Observatory clear sky chart from 2005-11-06 to 2025-01-07.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	16% 8% 2 5% 3 3 3 3 4 6% 46%	108976
	Night	20% 9% 2 5% 3 3 3 3 4 5% 41%	108789
Transparency	Day	39% 6% 11% 20% 16% 8%	108731
	Night	44% 6% 10% 18% 14% 8%	108623
Seeing	Day	21% 12% 29% 27% 10% 2	15174
	Night	24% 8% 20% 29% 16% 2	24258

By Month

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	29% 22% 4 7% 4 3 3 2 3 4 18%	2587
	11th to 20th	Day	37% 14% 3 7% 4 3 3 2 3 3 21%	2857
	21st to end	Day	34% 11% 3 7% 4 4 5% 3 4 5% 20%	3146
February	1st to 10th	Day	26% 11% 3 7% 4 4 4 3 5% 6% 26%	1710
	11th to 20th	Day	27% 11% 3 8% 5% 4 4 3 3 5% 27%	1665
	21st to end	Day	29% 14% 4 7% 4 4 3 3 4 5% 25%	1490
March	1st to 10th	Day	24% 21% 3 7% 4 3 3 3 3 4 24%	3442
	11th to 20th	Day	21% 9% 3 6% 4 3 3 2 4 5% 40%	3490
	21st to end	Day	29% 14% 3 8% 6% 5% 5% 3 5% 4 17%	3825
April	1st to 10th	Day	26% 12% 4 8% 4 5% 4 3 5% 5% 23%	2240
	11th to 20th	Day	25% 12% 3 6% 5% 4 4 3 5% 7% 27%	2267
	21st to end	Day	22% 7% 2 7% 5% 4 3 3 6% 9% 31%	2470
May	1st to 10th	Day	18% 7% 2 6% 4 4 4 3 4 6% 42%	4110
	11th to 20th	Day	9% 5% 2 4 2 3 2 2 4 6% 61%	4272
	21st to end	Day	10% 5% 2 4 3 3 3 3 6% 9% 51%	4813
June	1st to 10th	Day	17% 7% 2 5% 5% 4 4 4 5% 7% 40%	2660
	11th to 20th	Day	9% 5% 2 4 3 3 3 3 5% 7% 54%	2660
	21st to end	Day	6% 3 1 3 2 3 3 3 4 6% 66%	2660
July	1st to 10th	Day	1 1 1 2 1 1 1 1 2 3 85%	4420
	11th to 20th	Day	3 2 1 2 1 2 2 2 3 6% 77%	4335
	21st to end	Day	2 1 1 1 1 2 1 3 5% 83%	4455
August	1st to 10th	Day	1 1 1 2 2 3 3 2 4 8% 72%	4091
	11th to 20th	Day	3 3 2 3 2 2 2 2 5% 8% 69%	4026
	21st to end	Day	5% 3 1 3 2 2 2 2 4 7% 69%	4340
September	1st to 10th	Day	2 2 1 4 3 3 3 2 4 5% 73%	2280
	11th to 20th	Day	9% 4 2 5% 4 3 4 3 6% 6% 53%	2161
	21st to end	Day	9% 4 2 4 3 3 3 3 5% 7% 57%	2067
October	1st to 10th	Day	7% 3 2 3 2 2 3 3 5% 6% 64%	3180
	11th to 20th	Day	17% 8% 2 6% 5% 3 4 4 6% 9% 36%	3161
	21st to end	Day	21% 8% 3 7% 4 4 4 4 6% 6% 33%	3448
November	1st to 10th	Day	28% 9% 3 7% 5% 4 4 3 6% 6% 25%	1796
	11th to 20th	Day	26% 11% 3 8% 5% 4 5% 3 6% 7% 23%	1600
	21st to end	Day	23% 10% 3 7% 4 4 4 3 5% 6% 31%	1600
December	1st to 10th	Day	17% 6% 2 5% 3 4 4 3 5% 6% 44%	2620
	11th to 20th	Day	31% 13% 4 10% 6% 5% 5% 3 4 4 15%	3028
	21st to end	Day	38% 14% 4 10% 4 4 3 3 3 2 14%	4004
January	1st to 10th	Night	36% 15% 3 8% 5% 4 4 3 3 3 15%	4490
	11th to 20th	Night	36% 12% 4 6% 4 3 3 2 3 4 23%	4110
	21st to end	Night	41% 12% 3 7% 3 3 3 2 3 4 19%	4521
February	1st to 10th	Night	25% 10% 3 6% 5% 4 4 3 6% 7% 27%	2470
	11th to 20th	Night	25% 12% 4 6% 4 5% 3 3 4 5% 31%	2402
	21st to end	Night	27% 13% 3 6% 3 3 4 4 5% 4 27%	1961
March	1st to 10th	Night	23% 23% 3 7% 4 3 3 3 4 5% 22%	3432
	11th to 20th	Night	19% 12% 3 6% 4 2 3 2 4 7% 38%	3490
	21st to end	Night	28% 19% 4 8% 5% 3 3 3 3 4 19%	3828
April	1st to 10th	Night	25% 12% 4 7% 5% 4 4 4 4 6% 26%	1939
	11th to 20th	Night	22% 13% 3 5% 4 3 4 4 4 5% 33%	1855
	21st to end	Night	21% 8% 3 6% 3 4 4 3 6% 7% 34%	1710
May	1st to 10th	Night	17% 8% 2 5% 4 3 3 2 4 5% 47%	2860
	11th to 20th	Night	7% 5% 2 4 2 2 3 2 4 5% 64%	2622
	21st to end	Night	10% 8% 2 4 2 2 2 3 4 6% 56%	2762
June	1st to 10th	Night	17% 7% 2 5% 3 3 3 3 5% 7% 44%	1520
	11th to 20th	Night	7% 4 1 2 2 3 3 3 3 7% 64%	1520
	21st to end	Night	5% 4 1 3 2 2 2 2 3 5% 71%	1520
July	1st to 10th	Night	2 1 1 1 1 1 2 1 1 3 86%	2540
	11th to 20th	Night	2 1 1 2 2 2 3 3 3 10% 72%	2625
	21st to end	Night	2 2 1 1 1 1 1 2 3 84%	3109
August	1st to 10th	Night	1 1 1 2 2 2 4 2 4 8% 73%	2848
	11th to 20th	Night	2 2 1 4 3 3 4 3 5% 7% 67%	2812
	21st to end	Night	4 3 1 3 2 2 2 2 3 5% 74%	3333
September	1st to 10th	Night	2 3 1 2 2 2 2 2 4 5% 76%	1900
	11th to 20th	Night	6% 4 1 4 3 3 4 3 4 6% 60%	2014
	21st to end	Night	10% 5% 2 4 2 2 3 2 5% 8% 59%	2112
October	1st to 10th	Night	6% 3 2 4 3 3 3 3 4 6% 65%	3800
	11th to 20th	Night	12% 7% 2 7% 4 4 5% 4 5% 8% 42%	3777
	21st to end	Night	26% 9% 3 7% 4 4 4 2 4 5% 31%	4121
November	1st to 10th	Night	24% 10% 2 8% 4 4 4 3 5% 6% 30%	2498
	11th to 20th	Night	28% 12% 3 7% 5% 4 4 3 5% 5% 24%	2800
	21st to end	Night	24% 9% 2 6% 4 4 4 4 5% 6% 33%	2800
December	1st to 10th	Night	16% 8% 3 5% 4 3 4 3 5% 5% 45%	4560
	11th to 20th	Night	34% 12% 3 8% 5% 4 4 3 5% 6% 16%	5176
	21st to end	Night	36% 11% 3 8% 4 4 4 3 4 5% 19%	6952

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	72% 6% 9% 9% 3 1	2587
	11th to 20th	Day	69% 5% 4 10% 6% 6%	2857
	21st to end	Day	66% 7% 7% 9% 7% 4	3146
February	1st to 10th	Day	58% 7% 11% 15% 7% 2	1710
	11th to 20th	Day	61% 6% 10% 15% 7% 2	1674
	21st to end	Day	63% 6% 10% 13% 7% 1	1490
March	1st to 10th	Day	63% 7% 7% 18% 5%	3442
	11th to 20th	Day	46% 6% 15% 17% 13% 2	3490
	21st to end	Day	67% 11% 9% 8% 4	3825
April	1st to 10th	Day	63% 7% 11% 12% 7% 1	2240
	11th to 20th	Day	56% 8% 11% 14% 8% 2	2270
	21st to end	Day	49% 9% 14% 16% 11% 1	2470
May	1st to 10th	Day	40% 9% 12% 22% 13% 3	4110
	11th to 20th	Day	24% 4 11% 29% 29% 3	4275
	21st to end	Day	28% 8% 26% 33% 5%	4814
June	1st to 10th	Day	43% 6% 13% 22% 14% 1	2660
	11th to 20th	Day	29% 7% 15% 33% 13% 2	2660
	21st to end	Day	20% 4 13% 36% 22% 5%	2660
July	1st to 10th	Day	7% 2 6% 17% 25% 42%	4351
	11th to 20th	Day	10% 2 6% 17% 28% 38%	4260
	21st to end	Day	7% 2 8% 23% 46% 15%	4315
August	1st to 10th	Day	11% 3 11% 27% 38% 10%	4076
	11th to 20th	Day	14% 4 14% 37% 22% 8%	4065
	21st to end	Day	16% 4 12% 31% 29% 9%	4339
September	1st to 10th	Day	15% 3 9% 26% 31% 16%	2280
	11th to 20th	Day	29% 7% 13% 29% 17% 5%	2161
	21st to end	Day	27% 6% 12% 25% 21% 9%	2067
October	1st to 10th	Day	22% 6% 11% 18% 23% 21%	3180
	11th to 20th	Day	41% 6% 17% 20% 13% 3	3161
	21st to end	Day	48% 7% 10% 16% 14% 5%	3448
November	1st to 10th	Day	59% 8% 9% 12% 10% 2	1796
	11th to 20th	Day	60% 8% 11% 10% 6% 6%	1600
	21st to end	Day	55% 5% 8% 11% 12% 9%	1600
December	1st to 10th	Day	40% 5% 8% 20% 18% 10%	2620
	11th to 20th	Day	71% 6% 9% 8% 5% 1	3028
	21st to end	Day	77% 5% 5% 8% 4 2	4004
January	1st to 10th	Night	75% 6% 7% 7% 3 2	4490
	11th to 20th	Night	67% 5% 7% 9% 5% 6%	4110
	21st to end	Night	70% 4 6% 8% 8% 4	4521
February	1st to 10th	Night	55% 7% 13% 13% 9% 3	2470
	11th to 20th	Night	57% 5% 10% 17% 9% 2	2404
	21st to end	Night	58% 9% 10% 12% 8% 2	1961
March	1st to 10th	Night	64% 6% 9% 16% 5%	3432
	11th to 20th	Night	45% 8% 13% 15% 14% 5%	3490
	21st to end	Night	67% 9% 11% 10% 3	3828
April	1st to 10th	Night	58% 8% 11% 16% 6% 1	1939
	11th to 20th	Night	52% 7% 15% 14% 9% 3	1855
	21st to end	Night	47% 8% 13% 22% 9% 1	1710
May	1st to 10th	Night	37% 9% 12% 24% 14% 3	2860
	11th to 20th	Night	24% 5% 10% 30% 28% 3	2622
	21st to end	Night	26% 9% 27% 33% 5%	2762
June	1st to 10th	Night	40% 7% 12% 28% 12% 1	1520
	11th to 20th	Night	21% 6% 15% 39% 17% 2	1520
	21st to end	Night	17% 4 12% 38% 23% 6%	1520
July	1st to 10th	Night	7% 1 4 17% 26% 44%	2500
	11th to 20th	Night	9% 2 7% 15% 30% 37%	2577
	21st to end	Night	8% 1 7% 19% 47% 19%	3011
August	1st to 10th	Night	11% 3 9% 25% 38% 15%	2839
	11th to 20th	Night	14% 6% 11% 36% 23% 10%	2839
	21st to end	Night	15% 3 8% 33% 29% 12%	3333
September	1st to 10th	Night	12% 3 9% 24% 33% 18%	1900
	11th to 20th	Night	24% 6% 13% 31% 20% 7%	2014
	21st to end	Night	25% 6% 14% 21% 20% 14%	2112
October	1st to 10th	Night	21% 5% 10% 18% 20% 25%	3800
	11th to 20th	Night	38% 7% 16% 25% 11% 5%	3777
	21st to end	Night	55% 6% 8% 13% 13% 6%	4121
November	1st to 10th	Night	55% 7% 10% 13% 11% 5%	2498
	11th to 20th	Night	62% 7% 8% 12% 7% 5%	2800
	21st to end	Night	51% 7% 10% 11% 13% 9%	2800
December	1st to 10th	Night	40% 5% 7% 17% 19% 10%	4560
	11th to 20th	Night	68% 6% 10% 8% 6% 1	5176
	21st to end	Night	67% 7% 7% 14% 4 1	6952

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	53% 11% 19% 11% 5% 1	192
	11th to 20th	Day	42% 12% 18% 15% 11% 2	367
	21st to end	Day	36% 12% 24% 16% 11% 1	407
February	1st to 10th	Day	32% 13% 26% 20% 8%	370
	11th to 20th	Day	39% 15% 24% 19% 3 1	365
	21st to end	Day	38% 16% 23% 17% 4 1	328
March	1st to 10th	Day	41% 17% 22% 17% 3	460
	11th to 20th	Day	32% 14% 27% 17% 9% 2	460
	21st to end	Day	36% 18% 26% 16% 4	506
April	1st to 10th	Day	32% 15% 26% 21% 6%	460
	11th to 20th	Day	30% 19% 26% 19% 5% 2	452
	21st to end	Day	27% 18% 27% 20% 6% 1	460
May	1st to 10th	Day	17% 19% 35% 20% 9% 1	463
	11th to 20th	Day	25% 13% 28% 22% 10% 2	488
	21st to end	Day	18% 14% 35% 26% 7% 1	529
June	1st to 10th	Day	17% 14% 30% 27% 9% 2	490
	11th to 20th	Day	16% 19% 39% 21% 6%	490
	21st to end	Day	5% 7% 37% 39% 11% 1	490
July	1st to 10th	Day	5% 6% 37% 41% 11% 1	486
	11th to 20th	Day	4 5% 41% 38% 10% 2	484
	21st to end	Day	2 2 36% 43% 15% 2	531
August	1st to 10th	Day	1 2 31% 43% 19% 3	487
	11th to 20th	Day	4 3 30% 42% 19% 3	477
	21st to end	Day	6% 4 35% 38% 15% 2	539
September	1st to 10th	Day	4 5% 29% 42% 16% 4	490
	11th to 20th	Day	12% 10% 27% 32% 17% 2	490
	21st to end	Day	13% 9% 32% 31% 13% 2	490
October	1st to 10th	Day	13% 11% 27% 30% 16% 3	490
	11th to 20th	Day	21% 9% 26% 24% 17% 4	490
	21st to end	Day	23% 17% 24% 24% 10% 2	539
November	1st to 10th	Day	31% 15% 23% 19% 10% 2	384
	11th to 20th	Day	35% 14% 18% 19% 13% 3	200
	21st to end	Day	28% 14% 20% 25% 14%	200
December	1st to 10th	Day	25% 16% 20% 24% 13% 4	200
	11th to 20th	Day	45% 12% 18% 20% 5% 2	200
	21st to end	Day	47% 10% 20% 16% 6%	220
January	1st to 10th	Night	43% 12% 17% 17% 8% 1	784
	11th to 20th	Night	38% 10% 17% 21% 12% 3	760
	21st to end	Night	34% 7% 17% 28% 12% 2	836
February	1st to 10th	Night	31% 10% 19% 25% 15% 1	760
	11th to 20th	Night	33% 11% 18% 26% 11% 2	744
	21st to end	Night	36% 12% 18% 25% 8%	628
March	1st to 10th	Night	35% 13% 19% 22% 9% 2	760
	11th to 20th	Night	32% 9% 20% 24% 15% 1	760
	21st to end	Night	38% 13% 20% 20% 9% 1	836
April	1st to 10th	Night	31% 13% 20% 22% 13% 2	760
	11th to 20th	Night	29% 12% 22% 24% 12% 2	727
	21st to end	Night	25% 8% 22% 30% 15% 1	570
May	1st to 10th	Night	19% 9% 30% 29% 13% 1	570
	11th to 20th	Night	17% 9% 20% 31% 22% 2	441
	21st to end	Night	19% 9% 24% 32% 14% 3	411
June	1st to 10th	Night	19% 5% 26% 33% 16% 1	380
	11th to 20th	Night	9% 6% 38% 31% 14% 1	380
	21st to end	Night	8% 3 24% 42% 21% 2	380
July	1st to 10th	Night	4 23% 42% 28% 1	370
	11th to 20th	Night	3 1 29% 45% 21% 1	414
	21st to end	Night	2 25% 44% 25% 5%	624
August	1st to 10th	Night	1 1 15% 46% 32% 5%	567
	11th to 20th	Night	3 1 13% 45% 32% 6%	564
	21st to end	Night	5% 3 25% 38% 25% 4	736
September	1st to 10th	Night	3 3 18% 44% 29% 3	760
	11th to 20th	Night	7% 5% 17% 32% 31% 8%	760
	21st to end	Night	12% 6% 21% 36% 21% 4	760
October	1st to 10th	Night	12% 6% 23% 33% 22% 4	760
	11th to 20th	Night	19% 7% 19% 30% 21% 4	760
	21st to end	Night	24% 10% 19% 29% 14% 4	836
November	1st to 10th	Night	30% 8% 21% 26% 12% 2	780
	11th to 20th	Night	35% 10% 18% 26% 9% 1	800
	21st to end	Night	28% 11% 20% 29% 12% 1	800
December	1st to 10th	Night	29% 9% 21% 28% 11% 2	800
	11th to 20th	Night	42% 9% 18% 22% 9% 1	800
	21st to end	Night	47% 9% 19% 18% 6%	880

Page generated at 2025-01-04 00:23:57. Version ac07

Copyright © 2025 Attilla Danko.