Roseburg Airport
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Roseburg Airport clear sky chart from 2005-11-06 to 2024-11-03.

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	15% 8% 3 6% 4 4 4 3 5% 6% 42%	101459
	Night	17% 9% 3 7% 4 4 3 3 5% 6% 39%	97697
Transparency	Day	42% 6% 12% 20% 14% 6%	101209
	Night	46% 6% 13% 19% 12% 4	97536
Seeing	Day	18% 12% 24% 26% 15% 5%	14880
	Night	20% 7% 14% 31% 25% 3	23845

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	26% 16% 5% 10% 6% 5% 5% 3 5% 4 14%	2539
	11th to 20th	Day	35% 14% 3 9% 6% 4 4 3 4 5% 14%	2672
	21st to end	Day	25% 13% 4 8% 5% 5% 5% 4 6% 7% 19%	3146
February	1st to 10th	Day	22% 11% 3 8% 5% 5% 6% 6% 7% 7% 19%	1710
	11th to 20th	Day	23% 13% 4 10% 6% 4 5% 4 6% 5% 21%	1665
	21st to end	Day	25% 15% 5% 9% 6% 4 4 3 5% 6% 19%	1492
March	1st to 10th	Day	19% 13% 5% 12% 6% 6% 4 4 5% 6% 21%	3384
	11th to 20th	Day	16% 9% 2 7% 4 4 4 3 6% 7% 37%	3490
	21st to end	Day	22% 13% 4 9% 6% 5% 5% 5% 6% 7% 17%	3845
April	1st to 10th	Day	22% 14% 4 9% 7% 5% 5% 3 5% 5% 20%	2280
	11th to 20th	Day	20% 14% 4 10% 4 4 4 4 5% 5% 25%	2249
	21st to end	Day	21% 9% 4 7% 5% 4 5% 5% 5% 7% 29%	2441
May	1st to 10th	Day	17% 8% 3 7% 5% 5% 5% 4 6% 6% 35%	4168
	11th to 20th	Day	10% 5% 2 5% 3 3 3 3 4 6% 57%	4377
	21st to end	Day	14% 7% 2 6% 5% 5% 5% 4 6% 8% 39%	4813
June	1st to 10th	Day	18% 10% 3 7% 4 4 4 3 4 7% 36%	2660
	11th to 20th	Day	14% 7% 2 6% 4 5% 4 3 6% 7% 41%	2660
	21st to end	Day	7% 5% 1 4 3 3 3 2 5% 6% 60%	2660
July	1st to 10th	Day	3 2 1 2 1 1 1 2 2 3 81%	4420
	11th to 20th	Day	4 3 1 2 2 2 2 2 3 3 76%	4420
	21st to end	Day	3 4 1 2 2 2 2 2 3 4 75%	4582
August	1st to 10th	Day	3 4 1 4 2 2 3 2 3 5% 70%	4091
	11th to 20th	Day	3 5% 1 4 2 3 3 3 4 6% 65%	4026
	21st to end	Day	5% 5% 2 3 3 2 2 2 3 6% 67%	4282
September	1st to 10th	Day	5% 3 1 3 2 2 3 2 4 6% 68%	2280
	11th to 20th	Day	9% 6% 2 5% 2 3 4 3 5% 7% 53%	2237
	21st to end	Day	10% 5% 2 5% 3 4 4 3 5% 7% 52%	2024
October	1st to 10th	Day	13% 7% 3 7% 4 4 3 3 5% 6% 45%	1900
	11th to 20th	Day	14% 7% 3 7% 5% 4 5% 4 6% 7% 38%	1900
	21st to end	Day	18% 10% 3 9% 4 4 4 4 6% 7% 31%	2090
November	1st to 10th	Day	25% 10% 3 9% 5% 6% 4 4 6% 7% 21%	1674
	11th to 20th	Day	25% 10% 4 8% 7% 5% 5% 4 6% 6% 19%	1520
	21st to end	Day	24% 11% 3 7% 5% 5% 3 4 5% 8% 25%	1520
December	1st to 10th	Day	19% 9% 4 8% 6% 4 5% 5% 5% 7% 27%	1520
	11th to 20th	Day	23% 13% 3 9% 8% 5% 5% 4 7% 8% 17%	1928
	21st to end	Day	26% 16% 5% 10% 6% 5% 5% 3 6% 5% 12%	2794
January	1st to 10th	Night	28% 16% 5% 10% 6% 5% 4 4 5% 4 13%	4406
	11th to 20th	Night	32% 14% 3 9% 5% 4 4 3 4 4 17%	4288
	21st to end	Night	29% 15% 5% 9% 5% 4 4 2 4 5% 19%	4521
February	1st to 10th	Night	22% 13% 4 9% 5% 5% 5% 3 6% 7% 22%	2470
	11th to 20th	Night	23% 15% 4 7% 5% 4 3 3 5% 7% 25%	2402
	21st to end	Night	21% 15% 3 8% 6% 4 4 3 6% 6% 24%	1960
March	1st to 10th	Night	20% 15% 6% 10% 5% 4 5% 4 5% 6% 21%	3475
	11th to 20th	Night	14% 10% 3 8% 5% 4 3 3 6% 9% 35%	3490
	21st to end	Night	22% 15% 4 11% 6% 5% 5% 4 4 5% 19%	3808
April	1st to 10th	Night	24% 12% 4 8% 5% 5% 4 4 5% 6% 24%	1900
	11th to 20th	Night	19% 13% 3 7% 6% 5% 4 3 4 6% 30%	1879
	21st to end	Night	19% 9% 4 6% 5% 5% 4 5% 6% 7% 31%	1734
May	1st to 10th	Night	20% 11% 3 6% 5% 3 3 4 4 5% 36%	2797
	11th to 20th	Night	9% 5% 2 6% 3 3 3 3 4 5% 57%	2516
	21st to end	Night	16% 7% 2 5% 4 3 3 2 4 6% 48%	2762
June	1st to 10th	Night	16% 7% 2 5% 4 4 4 4 5% 7% 42%	1520
	11th to 20th	Night	10% 6% 3 5% 4 3 4 2 4 6% 53%	1520
	21st to end	Night	8% 2 1 2 2 2 3 2 3 5% 71%	1520
July	1st to 10th	Night	2 1 1 1 1 1 1 1 2 3 85%	2540
	11th to 20th	Night	2 2 1 2 2 2 2 1 2 3 82%	2540
	21st to end	Night	4 2 1 2 1 2 1 1 2 3 80%	2973
August	1st to 10th	Night	2 2 1 3 2 2 2 2 4 4 76%	2848
	11th to 20th	Night	3 3 1 3 3 4 3 2 4 6% 69%	2812
	21st to end	Night	5% 3 1 3 2 2 2 2 3 4 73%	3392
September	1st to 10th	Night	5% 2 1 2 1 2 2 2 4 5% 75%	1900
	11th to 20th	Night	7% 4 2 4 4 4 3 3 4 7% 59%	1938
	21st to end	Night	11% 5% 2 5% 3 3 3 2 5% 7% 55%	2156
October	1st to 10th	Night	10% 7% 2 6% 4 3 3 2 5% 6% 52%	2280
	11th to 20th	Night	13% 7% 3 7% 4 3 3 3 6% 7% 44%	2280
	21st to end	Night	19% 10% 3 7% 4 5% 4 3 4 6% 36%	2508
November	1st to 10th	Night	24% 9% 3 8% 5% 4 5% 3 6% 8% 25%	2444
	11th to 20th	Night	27% 10% 3 9% 5% 5% 5% 3 6% 6% 21%	2660
	21st to end	Night	22% 10% 3 7% 5% 4 4 3 6% 7% 29%	2660
December	1st to 10th	Night	22% 11% 3 8% 5% 4 3 4 6% 6% 28%	2660
	11th to 20th	Night	24% 14% 4 9% 5% 4 4 4 6% 7% 19%	3276
	21st to end	Night	24% 12% 4 11% 7% 6% 5% 4 7% 5% 15%	4862

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	71% 6% 11% 8% 2 1	2539
	11th to 20th	Day	71% 7% 6% 8% 4 4	2672
	21st to end	Day	62% 8% 12% 11% 6% 2	3146
February	1st to 10th	Day	60% 8% 14% 12% 5% 1	1710
	11th to 20th	Day	62% 8% 12% 13% 4 2	1674
	21st to end	Day	66% 7% 9% 11% 6% 1	1492
March	1st to 10th	Day	62% 6% 13% 16% 3	3384
	11th to 20th	Day	44% 8% 11% 25% 12% 1	3490
	21st to end	Day	62% 10% 16% 10% 3	3845
April	1st to 10th	Day	65% 7% 12% 12% 4	2280
	11th to 20th	Day	60% 8% 12% 12% 6% 2	2252
	21st to end	Day	53% 7% 16% 15% 7% 1	2441
May	1st to 10th	Day	45% 8% 16% 22% 9%	4168
	11th to 20th	Day	29% 4 16% 33% 17% 1	4380
	21st to end	Day	42% 10% 26% 21% 2	4814
June	1st to 10th	Day	49% 5% 17% 23% 6%	2660
	11th to 20th	Day	42% 7% 16% 27% 9% 1	2660
	21st to end	Day	25% 5% 15% 34% 17% 3	2660
July	1st to 10th	Day	12% 2 8% 17% 23% 38%	4351
	11th to 20th	Day	14% 3 5% 17% 30% 30%	4345
	21st to end	Day	14% 3 7% 23% 42% 12%	4437
August	1st to 10th	Day	18% 4 8% 25% 35% 10%	4076
	11th to 20th	Day	19% 4 12% 34% 24% 6%	4065
	21st to end	Day	20% 3 12% 28% 29% 7%	4281
September	1st to 10th	Day	19% 3 7% 27% 29% 14%	2280
	11th to 20th	Day	30% 5% 14% 27% 18% 7%	2237
	21st to end	Day	31% 4 14% 26% 18% 7%	2024
October	1st to 10th	Day	38% 6% 10% 20% 17% 9%	1900
	11th to 20th	Day	42% 7% 15% 18% 14% 4	1900
	21st to end	Day	51% 6% 11% 16% 13% 4	2090
November	1st to 10th	Day	61% 6% 11% 14% 7% 1	1674
	11th to 20th	Day	62% 7% 10% 10% 7% 3	1520
	21st to end	Day	57% 6% 11% 10% 13% 4	1520
December	1st to 10th	Day	54% 8% 10% 15% 12% 1	1520
	11th to 20th	Day	60% 8% 15% 12% 4	1928
	21st to end	Day	69% 7% 11% 9% 3 1	2794
January	1st to 10th	Night	72% 7% 9% 8% 3 1	4406
	11th to 20th	Night	66% 7% 8% 11% 4 4	4288
	21st to end	Night	69% 4 8% 12% 6% 2	4521
February	1st to 10th	Night	60% 6% 13% 13% 6% 1	2470
	11th to 20th	Night	59% 6% 12% 16% 5% 2	2404
	21st to end	Night	60% 7% 13% 13% 5% 2	1960
March	1st to 10th	Night	62% 6% 15% 15% 2	3475
	11th to 20th	Night	43% 9% 14% 24% 6% 4	3490
	21st to end	Night	65% 8% 16% 10% 1	3808
April	1st to 10th	Night	61% 6% 15% 13% 4	1900
	11th to 20th	Night	55% 7% 16% 14% 4 3	1879
	21st to end	Night	52% 8% 19% 15% 5% 1	1734
May	1st to 10th	Night	50% 7% 15% 19% 9% 1	2797
	11th to 20th	Night	31% 5% 14% 39% 11% 1	2516
	21st to end	Night	39% 7% 33% 19% 2	2762
June	1st to 10th	Night	41% 9% 16% 30% 4	1520
	11th to 20th	Night	34% 5% 21% 32% 7% 1	1520
	21st to end	Night	18% 4 19% 38% 18% 2	1520
July	1st to 10th	Night	8% 2 8% 20% 28% 34%	2500
	11th to 20th	Night	10% 2 5% 22% 37% 25%	2492
	21st to end	Night	12% 2 8% 29% 40% 9%	2880
August	1st to 10th	Night	13% 3 9% 31% 37% 8%	2839
	11th to 20th	Night	17% 5% 16% 35% 23% 4	2839
	21st to end	Night	17% 4 12% 30% 31% 6%	3392
September	1st to 10th	Night	14% 3 8% 33% 29% 13%	1900
	11th to 20th	Night	25% 6% 14% 31% 18% 6%	1938
	21st to end	Night	30% 5% 13% 27% 18% 8%	2156
October	1st to 10th	Night	32% 5% 13% 22% 20% 7%	2280
	11th to 20th	Night	38% 5% 18% 20% 16% 3	2280
	21st to end	Night	49% 6% 11% 16% 13% 4	2508
November	1st to 10th	Night	55% 7% 14% 13% 10% 1	2444
	11th to 20th	Night	62% 7% 10% 11% 8% 3	2660
	21st to end	Night	53% 6% 10% 14% 12% 5%	2660
December	1st to 10th	Night	54% 6% 11% 17% 10% 1	2660
	11th to 20th	Night	63% 7% 12% 13% 6%	3276
	21st to end	Night	64% 9% 13% 10% 3 1	4862

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	33% 17% 22% 16% 9% 2	180
	11th to 20th	Day	33% 14% 15% 21% 10% 8%	260
	21st to end	Day	25% 14% 23% 16% 18% 4	407
February	1st to 10th	Day	25% 12% 21% 24% 16% 2	370
	11th to 20th	Day	31% 16% 22% 20% 9% 2	365
	21st to end	Day	31% 18% 20% 23% 8% 1	346
March	1st to 10th	Day	30% 17% 23% 22% 8% 1	460
	11th to 20th	Day	25% 14% 23% 22% 15% 2	460
	21st to end	Day	28% 18% 25% 21% 8% 1	506
April	1st to 10th	Day	23% 20% 24% 20% 12% 1	460
	11th to 20th	Day	27% 18% 24% 19% 8% 3	452
	21st to end	Day	25% 19% 24% 20% 9% 3	460
May	1st to 10th	Day	20% 15% 29% 22% 11% 3	463
	11th to 20th	Day	24% 15% 24% 22% 10% 5%	488
	21st to end	Day	21% 13% 23% 25% 12% 5%	529
June	1st to 10th	Day	16% 16% 24% 25% 14% 5%	490
	11th to 20th	Day	12% 20% 32% 23% 10% 2	490
	21st to end	Day	5% 8% 32% 35% 16% 5%	490
July	1st to 10th	Day	4 7% 30% 36% 17% 6%	486
	11th to 20th	Day	3 7% 30% 39% 14% 7%	484
	21st to end	Day	3 3 29% 37% 21% 6%	531
August	1st to 10th	Day	4 3 26% 40% 19% 8%	487
	11th to 20th	Day	3 6% 20% 37% 24% 10%	477
	21st to end	Day	5% 7% 26% 32% 22% 9%	539
September	1st to 10th	Day	6% 7% 24% 31% 23% 9%	490
	11th to 20th	Day	10% 10% 24% 33% 18% 5%	490
	21st to end	Day	12% 8% 27% 26% 20% 7%	490
October	1st to 10th	Day	15% 11% 19% 27% 22% 7%	490
	11th to 20th	Day	16% 10% 18% 27% 23% 7%	490
	21st to end	Day	22% 12% 22% 22% 17% 5%	539
November	1st to 10th	Day	23% 15% 20% 24% 14% 4	293
	11th to 20th	Day	22% 11% 21% 26% 15% 6%	180
	21st to end	Day	26% 12% 15% 25% 21% 1	180
December	1st to 10th	Day	26% 10% 19% 23% 14% 8%	180
	11th to 20th	Day	32% 15% 16% 21% 12% 3	180
	21st to end	Day	33% 13% 16% 22% 14% 2	198
January	1st to 10th	Night	32% 11% 18% 22% 14% 3	760
	11th to 20th	Night	27% 12% 13% 26% 18% 5%	760
	21st to end	Night	26% 6% 14% 29% 21% 4	836
February	1st to 10th	Night	25% 9% 15% 29% 21% 2	760
	11th to 20th	Night	28% 10% 14% 29% 18% 1	744
	21st to end	Night	26% 10% 16% 32% 15%	628
March	1st to 10th	Night	29% 11% 16% 28% 15% 1	760
	11th to 20th	Night	21% 11% 15% 33% 19% 1	760
	21st to end	Night	29% 12% 17% 28% 14% 1	836
April	1st to 10th	Night	25% 13% 18% 25% 17% 2	760
	11th to 20th	Night	21% 11% 20% 28% 18% 2	751
	21st to end	Night	21% 8% 16% 31% 22% 2	594
May	1st to 10th	Night	21% 6% 16% 30% 24% 2	533
	11th to 20th	Night	13% 6% 14% 34% 32% 2	374
	21st to end	Night	17% 6% 17% 30% 27% 3	411
June	1st to 10th	Night	17% 5% 12% 35% 29% 1	380
	11th to 20th	Night	8% 6% 22% 38% 22% 3	380
	21st to end	Night	9% 2 10% 41% 38% 1	380
July	1st to 10th	Night	5% 1 8% 41% 43% 2	370
	11th to 20th	Night	2 1 13% 49% 34%	368
	21st to end	Night	3 2 6% 42% 42% 4	540
August	1st to 10th	Night	3 1 5% 37% 48% 6%	567
	11th to 20th	Night	3 1 6% 34% 50% 6%	564
	21st to end	Night	4 3 14% 37% 36% 6%	769
September	1st to 10th	Night	5% 2 15% 34% 41% 3	760
	11th to 20th	Night	8% 4 11% 35% 34% 8%	760
	21st to end	Night	12% 5% 13% 34% 32% 5%	760
October	1st to 10th	Night	11% 4 15% 36% 28% 7%	760
	11th to 20th	Night	14% 5% 12% 31% 32% 6%	760
	21st to end	Night	23% 7% 14% 30% 20% 6%	836
November	1st to 10th	Night	23% 7% 15% 31% 22% 2	748
	11th to 20th	Night	29% 7% 15% 29% 17% 2	760
	21st to end	Night	24% 9% 13% 31% 20% 3	760
December	1st to 10th	Night	26% 9% 12% 27% 21% 5%	760
	11th to 20th	Night	31% 10% 14% 27% 15% 3	760
	21st to end	Night	37% 10% 14% 25% 12% 1	836

Page generated at 2024-10-31 00:39:23. Version ac07

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