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 2026-10-29.

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	12% 7% 3 6% 4 4 4 3 5% 6% 46%	158790
	Night	15% 9% 3 7% 4 4 4 3 5% 6% 41%	150718
Transparency	Day	38% 6% 12% 22% 16% 7%	153594
	Night	43% 6% 13% 21% 13% 4	146912
Seeing	Day	17% 12% 24% 27% 15% 5%	17412
	Night	19% 8% 14% 32% 24% 3	26343

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% 15% 5% 11% 7% 5% 5% 4 5% 5% 12%	4722
	11th to 20th	Day	19% 8% 2 7% 5% 4 4 3 5% 8% 36%	4998
	21st to end	Day	16% 10% 4 8% 5% 5% 6% 4 6% 8% 30%	5843
February	1st to 10th	Day	23% 11% 3 8% 5% 5% 6% 6% 6% 7% 20%	1890
	11th to 20th	Day	23% 13% 4 10% 6% 5% 4 4 6% 6% 20%	1845
	21st to end	Day	25% 15% 5% 9% 6% 4 4 3 5% 6% 19%	1644
March	1st to 10th	Day	16% 11% 5% 11% 5% 6% 5% 4 6% 8% 22%	4976
	11th to 20th	Day	21% 13% 4 8% 4 5% 4 3 5% 6% 26%	5110
	21st to end	Day	22% 12% 4 9% 6% 5% 5% 4 6% 7% 18%	5640
April	1st to 10th	Day	21% 14% 4 9% 7% 5% 5% 3 6% 6% 20%	2520
	11th to 20th	Day	19% 13% 4 10% 4 4 4 4 5% 5% 27%	2489
	21st to end	Day	20% 9% 4 7% 5% 4 5% 4 5% 7% 30%	2699
May	1st to 10th	Day	10% 6% 2 6% 4 4 5% 4 6% 7% 47%	7735
	11th to 20th	Day	10% 7% 2 7% 4 4 4 4 6% 7% 45%	8160
	21st to end	Day	11% 6% 2 5% 4 4 4 4 6% 8% 47%	8992
June	1st to 10th	Day	16% 9% 3 7% 4 4 4 3 4 7% 39%	2940
	11th to 20th	Day	13% 7% 2 6% 4 4 4 3 6% 7% 44%	2940
	21st to end	Day	8% 5% 1 4 3 3 4 2 5% 6% 59%	2940
July	1st to 10th	Day	2 2 1 2 2 1 2 2 2 4 81%	8219
	11th to 20th	Day	3 3 1 2 2 2 2 2 2 3 78%	8220
	21st to end	Day	2 3 1 3 2 2 2 2 3 4 76%	8532
August	1st to 10th	Day	2 3 1 3 2 2 2 2 3 5% 75%	7547
	11th to 20th	Day	4 4 1 4 2 3 3 3 4 6% 65%	7563
	21st to end	Day	3 4 1 3 3 2 3 3 5% 6% 67%	7927
September	1st to 10th	Day	5% 3 1 3 3 2 3 3 4 6% 66%	2520
	11th to 20th	Day	8% 6% 3 5% 3 3 4 3 5% 7% 52%	2473
	21st to end	Day	10% 5% 2 5% 3 3 4 3 5% 7% 52%	2236
October	1st to 10th	Day	8% 6% 3 6% 4 3 3 2 4 6% 55%	3380
	11th to 20th	Day	11% 7% 3 7% 5% 5% 5% 4 6% 8% 37%	3361
	21st to end	Day	17% 10% 4 10% 4 5% 5% 5% 6% 8% 27%	3639
November	1st to 10th	Day	24% 10% 3 9% 5% 6% 4 4 6% 7% 21%	1830
	11th to 20th	Day	25% 11% 4 9% 7% 6% 5% 4 6% 6% 17%	1680
	21st to end	Day	23% 10% 3 8% 5% 5% 4 4 5% 8% 25%	1680
December	1st to 10th	Day	16% 7% 3 6% 5% 4 5% 5% 6% 8% 36%	2700
	11th to 20th	Day	27% 13% 4 9% 6% 5% 5% 3 6% 7% 15%	3108
	21st to end	Day	29% 16% 5% 11% 6% 5% 5% 3 5% 4 9%	4092
January	1st to 10th	Night	31% 15% 5% 10% 5% 5% 5% 4 5% 5% 11%	8172
	11th to 20th	Night	18% 9% 3 8% 4 4 5% 4 7% 10% 28%	7958
	21st to end	Night	18% 11% 4 8% 5% 5% 4 3 4 5% 31%	8371
February	1st to 10th	Night	22% 13% 4 9% 5% 5% 5% 3 6% 7% 21%	2730
	11th to 20th	Night	23% 15% 4 8% 5% 4 3 3 5% 6% 24%	2662
	21st to end	Night	21% 15% 3 8% 5% 4 4 3 6% 6% 25%	2160
March	1st to 10th	Night	19% 15% 5% 10% 5% 4 5% 4 5% 7% 21%	5123
	11th to 20th	Night	17% 14% 4 10% 5% 5% 4 3 5% 7% 25%	5110
	21st to end	Night	23% 14% 4 10% 6% 5% 5% 4 5% 6% 19%	5576
April	1st to 10th	Night	22% 13% 4 7% 5% 5% 4 4 5% 6% 24%	2100
	11th to 20th	Night	19% 12% 3 7% 6% 5% 4 3 5% 6% 31%	2079
	21st to end	Night	19% 9% 3 6% 5% 5% 4 5% 6% 6% 33%	1916
May	1st to 10th	Night	14% 8% 2 5% 4 3 3 3 5% 6% 48%	5204
	11th to 20th	Night	10% 8% 3 8% 5% 4 4 3 4 6% 45%	4700
	21st to end	Night	12% 6% 2 6% 3 3 3 2 4 6% 51%	5181
June	1st to 10th	Night	15% 7% 2 5% 4 3 4 4 5% 6% 45%	1680
	11th to 20th	Night	9% 6% 2 5% 4 3 4 2 4 6% 55%	1680
	21st to end	Night	9% 3 1 3 2 2 3 2 3 5% 69%	1680
July	1st to 10th	Night	2 1 1 1 1 2 3 2 3 5% 79%	4740
	11th to 20th	Night	1 2 1 2 1 2 1 1 2 2 84%	4740
	21st to end	Night	3 2 1 2 2 2 2 1 2 3 80%	5561
August	1st to 10th	Night	2 2 1 2 2 2 2 2 3 4 79%	5275
	11th to 20th	Night	4 3 1 3 3 3 3 3 4 5% 68%	5292
	21st to end	Night	3 3 1 3 2 2 2 2 4 5% 73%	6312
September	1st to 10th	Night	5% 3 1 3 1 2 3 2 4 5% 71%	2100
	11th to 20th	Night	7% 4 2 4 3 3 3 3 4 7% 59%	2142
	21st to end	Night	10% 5% 2 5% 3 3 3 2 5% 7% 55%	2383
October	1st to 10th	Night	7% 6% 2 5% 3 3 2 2 4 5% 61%	4040
	11th to 20th	Night	10% 7% 3 8% 4 4 4 3 6% 8% 44%	4017
	21st to end	Night	18% 11% 5% 10% 6% 5% 4 4 4 6% 28%	4349
November	1st to 10th	Night	23% 9% 3 7% 5% 4 5% 3 6% 8% 25%	2683
	11th to 20th	Night	27% 11% 4 10% 5% 5% 5% 3 5% 6% 20%	2940
	21st to end	Night	21% 10% 3 8% 5% 4 4 4 6% 8% 28%	2940
December	1st to 10th	Night	14% 8% 2 7% 4 5% 4 4 7% 8% 36%	4700
	11th to 20th	Night	27% 14% 5% 10% 5% 4 4 4 5% 7% 15%	5316
	21st to end	Night	26% 13% 4 10% 6% 6% 5% 4 7% 6% 13%	7106

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	4723
	11th to 20th	Day	44% 6% 6% 21% 14% 10%	4998
	21st to end	Day	50% 6% 9% 15% 13% 7%	5843
February	1st to 10th	Day	59% 8% 14% 13% 5% 1	1890
	11th to 20th	Day	62% 8% 12% 12% 5% 2	1854
	21st to end	Day	66% 7% 9% 11% 7% 1	1644
March	1st to 10th	Day	56% 7% 13% 20% 4	4976
	11th to 20th	Day	56% 7% 9% 18% 8% 1	5110
	21st to end	Day	61% 9% 16% 12% 2	5640
April	1st to 10th	Day	63% 7% 13% 13% 4	2520
	11th to 20th	Day	58% 7% 12% 14% 7% 2	2492
	21st to end	Day	52% 7% 16% 17% 8% 1	2699
May	1st to 10th	Day	34% 7% 14% 28% 17%	7735
	11th to 20th	Day	35% 7% 18% 29% 10% 1	8163
	21st to end	Day	34% 8% 23% 27% 8%	8994
June	1st to 10th	Day	46% 5% 16% 25% 7%	2940
	11th to 20th	Day	39% 6% 15% 27% 12% 1	2940
	21st to end	Day	26% 5% 15% 33% 17% 3	2940
July	1st to 10th	Day	11% 3 9% 30% 26% 21%	8151
	11th to 20th	Day	13% 2 5% 15% 30% 35%	8145
	21st to end	Day	14% 3 8% 34% 34% 7%	8342
August	1st to 10th	Day	14% 3 6% 20% 38% 21%	5976
	11th to 20th	Day	19% 5% 12% 37% 23% 5%	5962
	21st to end	Day	19% 4 11% 33% 28% 6%	6218
September	1st to 10th	Day	21% 4 8% 27% 27% 14%	2520
	11th to 20th	Day	30% 5% 14% 27% 18% 6%	2473
	21st to end	Day	31% 4 14% 26% 18% 7%	2236
October	1st to 10th	Day	30% 5% 9% 20% 20% 16%	3380
	11th to 20th	Day	40% 8% 17% 22% 10% 3	3361
	21st to end	Day	51% 7% 11% 18% 11% 2	3639
November	1st to 10th	Day	60% 7% 11% 15% 7% 1	1830
	11th to 20th	Day	64% 7% 10% 9% 7% 3	1680
	21st to end	Day	56% 7% 11% 11% 13% 3	1680
December	1st to 10th	Day	43% 7% 9% 19% 19% 4	2700
	11th to 20th	Day	65% 7% 13% 11% 3 1	3108
	21st to end	Day	74% 7% 9% 7% 2 1	4092
January	1st to 10th	Night	71% 7% 8% 10% 2 1	8172
	11th to 20th	Night	44% 6% 10% 24% 12% 4	7958
	21st to end	Night	54% 4 6% 15% 13% 7%	8371
February	1st to 10th	Night	60% 7% 13% 13% 6% 1	2730
	11th to 20th	Night	60% 6% 11% 15% 5% 1	2664
	21st to end	Night	59% 6% 13% 14% 5% 2	2160
March	1st to 10th	Night	60% 7% 15% 14% 4	5123
	11th to 20th	Night	56% 9% 11% 17% 5% 3	5110
	21st to end	Night	63% 8% 17% 10% 2	5576
April	1st to 10th	Night	60% 7% 16% 13% 4	2100
	11th to 20th	Night	54% 7% 16% 16% 5% 3	2079
	21st to end	Night	51% 8% 18% 17% 5% 1	1916
May	1st to 10th	Night	37% 6% 17% 31% 10%	5202
	11th to 20th	Night	39% 7% 15% 32% 6%	4700
	21st to end	Night	34% 6% 29% 28% 3	5182
June	1st to 10th	Night	40% 8% 16% 31% 6%	1680
	11th to 20th	Night	33% 5% 20% 33% 9% 2	1680
	21st to end	Night	20% 4 19% 37% 18% 2	1680
July	1st to 10th	Night	10% 3 12% 33% 24% 18%	4700
	11th to 20th	Night	10% 2 5% 21% 36% 27%	4692
	21st to end	Night	12% 2 12% 39% 30% 5%	5439
August	1st to 10th	Night	9% 2 7% 25% 40% 17%	4169
	11th to 20th	Night	16% 5% 16% 40% 20% 3	4169
	21st to end	Night	15% 4 11% 42% 24% 4	4944
September	1st to 10th	Night	17% 3 10% 32% 27% 12%	2100
	11th to 20th	Night	25% 6% 15% 32% 17% 6%	2142
	21st to end	Night	29% 5% 14% 27% 19% 7%	2383
October	1st to 10th	Night	26% 4 10% 22% 29% 8%	4040
	11th to 20th	Night	37% 6% 22% 22% 10% 2	4017
	21st to end	Night	55% 7% 11% 16% 9% 2	4349
November	1st to 10th	Night	54% 7% 15% 13% 10% 1	2683
	11th to 20th	Night	63% 7% 10% 11% 7% 2	2940
	21st to end	Night	54% 6% 10% 14% 12% 4	2940
December	1st to 10th	Night	41% 6% 11% 22% 18% 2	4700
	11th to 20th	Night	68% 6% 12% 10% 4	5316
	21st to end	Night	65% 9% 14% 9% 2 1	7106

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	35% 16% 21% 18% 9% 2	220
	11th to 20th	Day	28% 12% 14% 23% 13% 10%	309
	21st to end	Day	23% 13% 23% 18% 18% 5%	473
February	1st to 10th	Day	25% 13% 20% 24% 17% 2	430
	11th to 20th	Day	30% 16% 22% 21% 8% 2	425
	21st to end	Day	31% 18% 19% 23% 8% 1	402
March	1st to 10th	Day	27% 17% 24% 23% 9% 1	540
	11th to 20th	Day	25% 15% 23% 23% 13% 2	540
	21st to end	Day	28% 18% 24% 20% 9% 2	594
April	1st to 10th	Day	22% 18% 24% 21% 13% 2	540
	11th to 20th	Day	24% 18% 25% 19% 10% 4	532
	21st to end	Day	23% 18% 25% 21% 10% 4	540
May	1st to 10th	Day	18% 14% 28% 23% 12% 4	543
	11th to 20th	Day	22% 17% 25% 21% 10% 4	568
	21st to end	Day	20% 13% 24% 26% 12% 5%	617
June	1st to 10th	Day	15% 16% 24% 26% 14% 6%	570
	11th to 20th	Day	11% 19% 32% 25% 11% 3	570
	21st to end	Day	6% 8% 30% 35% 16% 5%	570
July	1st to 10th	Day	4 6% 29% 36% 18% 6%	566
	11th to 20th	Day	3 6% 31% 38% 15% 7%	564
	21st to end	Day	3 4 27% 38% 21% 7%	619
August	1st to 10th	Day	3 3 26% 40% 19% 9%	567
	11th to 20th	Day	3 6% 21% 36% 24% 10%	557
	21st to end	Day	4 7% 26% 32% 21% 11%	627
September	1st to 10th	Day	7% 7% 24% 30% 22% 10%	570
	11th to 20th	Day	9% 10% 25% 33% 18% 6%	570
	21st to end	Day	12% 8% 27% 26% 21% 8%	570
October	1st to 10th	Day	15% 10% 18% 27% 21% 9%	570
	11th to 20th	Day	15% 10% 19% 28% 23% 6%	570
	21st to end	Day	21% 12% 22% 23% 18% 4	616
November	1st to 10th	Day	23% 14% 20% 23% 16% 4	341
	11th to 20th	Day	24% 12% 22% 24% 13% 5%	220
	21st to end	Day	22% 12% 14% 25% 25% 2	220
December	1st to 10th	Day	22% 12% 17% 24% 16% 8%	220
	11th to 20th	Day	31% 15% 18% 21% 11% 4	220
	21st to end	Day	33% 14% 17% 21% 12% 3	242
January	1st to 10th	Night	33% 11% 17% 23% 13% 3	840
	11th to 20th	Night	25% 11% 12% 27% 20% 5%	840
	21st to end	Night	24% 6% 15% 30% 21% 4	924
February	1st to 10th	Night	24% 10% 16% 29% 20% 2	840
	11th to 20th	Night	29% 10% 15% 29% 17% 1	824
	21st to end	Night	26% 11% 16% 32% 15%	692
March	1st to 10th	Night	28% 12% 16% 30% 14% 1	840
	11th to 20th	Night	21% 12% 16% 33% 17% 1	840
	21st to end	Night	28% 12% 17% 28% 14% 1	924
April	1st to 10th	Night	24% 13% 18% 26% 18% 2	840
	11th to 20th	Night	21% 11% 19% 28% 18% 2	831
	21st to end	Night	21% 8% 16% 32% 21% 2	656
May	1st to 10th	Night	20% 7% 16% 31% 24% 2	589
	11th to 20th	Night	13% 7% 15% 35% 29% 2	414
	21st to end	Night	16% 7% 16% 32% 27% 3	455
June	1st to 10th	Night	15% 6% 15% 34% 28% 2	420
	11th to 20th	Night	7% 5% 22% 40% 22% 3	420
	21st to end	Night	10% 3 10% 41% 36% 1	420
July	1st to 10th	Night	5% 1 9% 42% 42% 2	410
	11th to 20th	Night	2 1 15% 49% 32%	408
	21st to end	Night	2 2 6% 42% 43% 5%	598
August	1st to 10th	Night	3 1 6% 38% 47% 6%	627
	11th to 20th	Night	3 1 6% 35% 49% 5%	624
	21st to end	Night	4 3 14% 37% 36% 6%	851
September	1st to 10th	Night	6% 2 15% 33% 40% 3	840
	11th to 20th	Night	8% 4 11% 35% 34% 8%	840
	21st to end	Night	12% 5% 13% 35% 31% 5%	840
October	1st to 10th	Night	11% 4 15% 35% 28% 7%	840
	11th to 20th	Night	14% 5% 13% 32% 30% 6%	840
	21st to end	Night	21% 7% 15% 30% 21% 5%	912
November	1st to 10th	Night	23% 8% 15% 31% 22% 2	820
	11th to 20th	Night	29% 9% 16% 28% 16% 2	840
	21st to end	Night	23% 9% 13% 32% 20% 3	840
December	1st to 10th	Night	24% 10% 12% 28% 21% 5%	840
	11th to 20th	Night	32% 10% 14% 26% 15% 3	840
	21st to end	Night	37% 11% 15% 24% 12% 1	924

Page generated at 2026-10-26 01:37:47. Version ac07

Copyright © 2026 Attilla Danko.