Yaquina Bay State Recreation Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Yaquina Bay State Recreation Site clear sky chart from 2005-11-06 to 2025-05-26.

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	22% 10% 3 7% 4 4 4 3 5% 6% 32%	118700
	Night	25% 12% 3 7% 4 4 3 3 4 5% 29%	119383
Transparency	Day	51% 6% 12% 16% 11% 3	118448
	Night	57% 6% 10% 14% 10% 4	119224
Seeing	Day	26% 11% 24% 25% 11% 3	15755
	Night	30% 8% 15% 26% 18% 3	24441

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	41% 16% 4 9% 5% 3 3 2 3 3 11%	3639
	11th to 20th	Day	30% 8% 3 5% 4 3 3 2 3 6% 33%	3778
	21st to end	Day	32% 8% 2 6% 3 3 3 3 4 4 31%	4510
February	1st to 10th	Day	35% 13% 3 8% 5% 4 4 3 4 6% 16%	1800
	11th to 20th	Day	32% 13% 2 8% 5% 5% 4 4 5% 4 18%	1755
	21st to end	Day	31% 17% 5% 7% 5% 3 3 3 4 5% 17%	1515
March	1st to 10th	Day	20% 18% 4 9% 6% 5% 5% 4 6% 7% 17%	4924
	11th to 20th	Day	31% 14% 4 7% 4 3 3 2 3 4 23%	5000
	21st to end	Day	30% 15% 4 11% 6% 5% 5% 4 5% 5% 10%	5486
April	1st to 10th	Day	31% 13% 4 8% 5% 4 5% 4 5% 6% 15%	2390
	11th to 20th	Day	26% 11% 3 8% 6% 4 3 4 4 6% 24%	2421
	21st to end	Day	27% 9% 3 7% 5% 4 5% 4 5% 6% 23%	2600
May	1st to 10th	Day	22% 10% 3 7% 5% 4 3 3 4 6% 34%	4325
	11th to 20th	Day	13% 8% 2 6% 4 4 4 3 6% 8% 42%	4517
	21st to end	Day	22% 9% 3 7% 5% 4 6% 4 7% 8% 25%	4886
June	1st to 10th	Day	27% 9% 3 6% 4 4 3 3 5% 6% 29%	2660
	11th to 20th	Day	21% 9% 3 6% 6% 4 5% 4 6% 8% 29%	2707
	21st to end	Day	13% 7% 2 6% 4 4 3 3 5% 8% 44%	2850
July	1st to 10th	Day	5% 4 2 3 3 2 3 2 4 8% 64%	4590
	11th to 20th	Day	7% 6% 2 5% 3 2 3 2 4 7% 58%	4420
	21st to end	Day	7% 6% 2 5% 3 3 3 3 5% 8% 57%	4617
August	1st to 10th	Day	5% 10% 3 7% 4 4 4 3 5% 8% 46%	4091
	11th to 20th	Day	9% 8% 4 7% 5% 5% 5% 4 5% 9% 41%	4026
	21st to end	Day	6% 6% 2 6% 3 4 4 4 5% 9% 53%	4372
September	1st to 10th	Day	7% 5% 2 5% 2 3 4 3 5% 8% 56%	2280
	11th to 20th	Day	12% 8% 3 6% 4 4 4 4 6% 9% 42%	2199
	21st to end	Day	18% 6% 2 5% 3 3 4 4 5% 7% 42%	2047
October	1st to 10th	Day	18% 6% 2 4 3 3 3 3 4 6% 49%	3180
	11th to 20th	Day	22% 10% 4 8% 5% 5% 4 4 5% 7% 27%	3161
	21st to end	Day	29% 9% 3 7% 4 4 4 3 6% 7% 24%	3448
November	1st to 10th	Day	33% 11% 3 9% 4 4 4 3 6% 5% 19%	1654
	11th to 20th	Day	35% 10% 3 6% 5% 3 5% 3 5% 5% 21%	1600
	21st to end	Day	31% 10% 3 7% 5% 3 4 3 5% 5% 24%	1600
December	1st to 10th	Day	23% 7% 2 6% 5% 3 3 3 4 5% 39%	2620
	11th to 20th	Day	36% 13% 3 10% 5% 5% 4 3 3 4 13%	3028
	21st to end	Day	44% 16% 4 8% 3 3 3 2 3 4 10%	4004
January	1st to 10th	Night	40% 15% 3 8% 5% 4 3 3 3 4 12%	6306
	11th to 20th	Night	27% 11% 3 6% 3 3 3 3 3 5% 33%	6171
	21st to end	Night	35% 10% 3 5% 3 2 2 2 3 3 32%	6468
February	1st to 10th	Night	32% 13% 4 9% 6% 4 4 4 4 5% 16%	2600
	11th to 20th	Night	31% 13% 3 9% 4 3 3 4 4 4 23%	2532
	21st to end	Night	32% 14% 3 8% 5% 3 3 3 4 4 20%	2115
March	1st to 10th	Night	21% 18% 4 10% 6% 6% 5% 3 4 6% 16%	4956
	11th to 20th	Night	28% 15% 4 9% 5% 4 3 3 3 3 24%	5000
	21st to end	Night	31% 18% 4 10% 6% 4 4 3 3 4 12%	5489
April	1st to 10th	Night	30% 14% 3 8% 6% 4 3 3 4 5% 20%	2010
	11th to 20th	Night	24% 13% 3 7% 5% 4 4 4 5% 5% 25%	1922
	21st to end	Night	26% 13% 3 7% 4 4 4 3 5% 6% 25%	1800
May	1st to 10th	Night	26% 10% 3 6% 3 3 3 3 4 5% 35%	2861
	11th to 20th	Night	17% 9% 3 8% 5% 4 3 3 5% 8% 36%	2596
	21st to end	Night	23% 12% 3 7% 4 3 4 3 4 6% 30%	2805
June	1st to 10th	Night	22% 9% 3 7% 6% 5% 4 4 5% 6% 29%	1520
	11th to 20th	Night	19% 12% 3 8% 4 3 4 4 6% 8% 32%	1464
	21st to end	Night	15% 12% 3 6% 3 3 2 3 5% 6% 42%	1330
July	1st to 10th	Night	5% 8% 3 5% 2 2 2 2 3 5% 65%	2365
	11th to 20th	Night	8% 10% 3 6% 3 3 3 2 4 6% 53%	2540
	21st to end	Night	9% 13% 4 7% 3 3 2 2 3 6% 48%	2938
August	1st to 10th	Night	6% 20% 5% 10% 4 3 3 3 4 7% 36%	2848
	11th to 20th	Night	8% 17% 5% 8% 4 3 4 2 4 7% 39%	2812
	21st to end	Night	10% 8% 2 5% 3 2 3 2 4 7% 53%	3298
September	1st to 10th	Night	11% 7% 2 4 3 2 3 3 4 6% 55%	1900
	11th to 20th	Night	14% 9% 3 7% 4 4 4 3 4 5% 43%	1980
	21st to end	Night	16% 7% 2 5% 3 3 4 4 4 8% 44%	2132
October	1st to 10th	Night	13% 7% 3 6% 4 3 4 3 5% 6% 47%	3800
	11th to 20th	Night	20% 11% 4 8% 5% 4 5% 4 5% 7% 27%	3777
	21st to end	Night	28% 10% 3 8% 4 5% 4 3 4 5% 25%	4121
November	1st to 10th	Night	32% 9% 3 8% 4 4 5% 3 5% 6% 22%	2639
	11th to 20th	Night	38% 8% 3 7% 4 4 4 3 4 4 20%	2800
	21st to end	Night	27% 11% 3 7% 5% 4 4 3 4 5% 27%	2800
December	1st to 10th	Night	22% 9% 2 6% 3 3 3 3 4 5% 39%	4560
	11th to 20th	Night	41% 13% 4 8% 4 3 3 2 4 5% 13%	5176
	21st to end	Night	40% 14% 3 8% 5% 4 3 2 3 4 14%	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	78% 5% 5% 7% 4 1	3639
	11th to 20th	Day	54% 3 7% 21% 11% 3	3778
	21st to end	Day	58% 4 6% 11% 15% 5%	4510
February	1st to 10th	Day	71% 5% 9% 10% 4 1	1800
	11th to 20th	Day	70% 6% 9% 8% 5% 2	1764
	21st to end	Day	71% 4 9% 9% 6% 2	1515
March	1st to 10th	Day	63% 6% 17% 10% 4	4924
	11th to 20th	Day	64% 7% 7% 13% 8% 1	5000
	21st to end	Day	74% 6% 12% 5% 2	5486
April	1st to 10th	Day	70% 6% 12% 9% 3	2390
	11th to 20th	Day	60% 6% 11% 14% 7% 2	2424
	21st to end	Day	60% 9% 11% 15% 5% 1	2600
May	1st to 10th	Day	50% 8% 17% 14% 12%	4325
	11th to 20th	Day	35% 11% 21% 23% 9% 1	4520
	21st to end	Day	52% 14% 23% 10% 1	4887
June	1st to 10th	Day	56% 6% 15% 17% 6%	2660
	11th to 20th	Day	52% 9% 18% 16% 4	2707
	21st to end	Day	37% 8% 19% 24% 9% 3	2850
July	1st to 10th	Day	19% 5% 11% 14% 26% 26%	4520
	11th to 20th	Day	24% 6% 7% 20% 32% 11%	4345
	21st to end	Day	22% 5% 13% 30% 25% 4	4471
August	1st to 10th	Day	31% 7% 11% 25% 19% 8%	4076
	11th to 20th	Day	37% 7% 19% 24% 11% 2	4065
	21st to end	Day	28% 7% 17% 26% 19% 4	4371
September	1st to 10th	Day	26% 6% 13% 28% 17% 10%	2280
	11th to 20th	Day	40% 8% 16% 18% 14% 5%	2199
	21st to end	Day	41% 7% 14% 20% 14% 5%	2047
October	1st to 10th	Day	38% 4 7% 25% 24% 3	3180
	11th to 20th	Day	57% 5% 13% 14% 10% 1	3161
	21st to end	Day	58% 5% 10% 16% 9% 2	3448
November	1st to 10th	Day	68% 5% 9% 13% 5%	1654
	11th to 20th	Day	66% 7% 10% 8% 6% 4	1600
	21st to end	Day	62% 5% 8% 12% 9% 4	1600
December	1st to 10th	Day	49% 4 9% 15% 22% 1	2620
	11th to 20th	Day	77% 5% 9% 6% 3	3028
	21st to end	Day	79% 5% 8% 5% 2 1	4004
January	1st to 10th	Night	78% 4 6% 6% 4 2	6306
	11th to 20th	Night	54% 4 8% 19% 12% 3	6171
	21st to end	Night	60% 2 5% 9% 16% 8%	6468
February	1st to 10th	Night	70% 6% 9% 9% 4 1	2600
	11th to 20th	Night	66% 5% 9% 10% 7% 2	2534
	21st to end	Night	68% 5% 9% 10% 6% 2	2115
March	1st to 10th	Night	68% 6% 10% 12% 4	4956
	11th to 20th	Night	65% 6% 8% 11% 9% 1	5000
	21st to end	Night	74% 7% 11% 7% 1	5489
April	1st to 10th	Night	68% 6% 10% 11% 5%	2010
	11th to 20th	Night	59% 8% 10% 15% 6% 3	1922
	21st to end	Night	59% 8% 10% 15% 6% 2	1800
May	1st to 10th	Night	51% 7% 13% 20% 8% 1	2861
	11th to 20th	Night	37% 16% 14% 21% 11% 2	2596
	21st to end	Night	51% 13% 25% 9% 2	2805
June	1st to 10th	Night	52% 9% 13% 21% 4	1520
	11th to 20th	Night	48% 10% 16% 21% 4	1464
	21st to end	Night	41% 8% 15% 26% 7% 3	1330
July	1st to 10th	Night	22% 5% 8% 12% 23% 29%	2326
	11th to 20th	Night	29% 6% 8% 16% 25% 17%	2492
	21st to end	Night	31% 6% 10% 24% 23% 7%	2846
August	1st to 10th	Night	41% 8% 10% 21% 13% 8%	2839
	11th to 20th	Night	41% 7% 17% 22% 9% 4	2839
	21st to end	Night	31% 7% 13% 23% 21% 4	3298
September	1st to 10th	Night	28% 6% 12% 26% 18% 10%	1900
	11th to 20th	Night	42% 8% 12% 19% 12% 7%	1980
	21st to end	Night	37% 7% 14% 19% 16% 7%	2132
October	1st to 10th	Night	36% 6% 9% 26% 20% 3	3800
	11th to 20th	Night	56% 5% 14% 14% 9% 2	3777
	21st to end	Night	61% 5% 9% 15% 8% 2	4121
November	1st to 10th	Night	64% 6% 9% 13% 7% 1	2639
	11th to 20th	Night	68% 5% 9% 8% 7% 4	2800
	21st to end	Night	60% 5% 8% 10% 10% 6%	2800
December	1st to 10th	Night	48% 4 8% 16% 21% 3	4560
	11th to 20th	Night	76% 5% 7% 7% 4 1	5176
	21st to end	Night	74% 7% 9% 8% 2 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	52% 14% 18% 12% 6%	200
	11th to 20th	Day	45% 8% 18% 20% 6% 2	260
	21st to end	Day	40% 9% 15% 22% 12% 2	440
February	1st to 10th	Day	43% 10% 17% 20% 9% 1	400
	11th to 20th	Day	41% 13% 19% 20% 7% 1	395
	21st to end	Day	38% 14% 22% 17% 8%	347
March	1st to 10th	Day	40% 15% 19% 20% 6% 1	500
	11th to 20th	Day	35% 13% 20% 20% 9% 3	500
	21st to end	Day	38% 18% 21% 14% 8% 1	550
April	1st to 10th	Day	38% 12% 21% 21% 7% 1	500
	11th to 20th	Day	31% 17% 24% 17% 8% 2	492
	21st to end	Day	29% 15% 27% 21% 6% 2	500
May	1st to 10th	Day	22% 15% 29% 22% 10% 2	503
	11th to 20th	Day	27% 15% 25% 20% 9% 2	528
	21st to end	Day	21% 13% 27% 26% 9% 3	550
June	1st to 10th	Day	28% 11% 23% 26% 10% 3	490
	11th to 20th	Day	22% 15% 32% 22% 8% 2	537
	21st to end	Day	11% 9% 32% 36% 10% 3	680
July	1st to 10th	Day	10% 6% 29% 39% 13% 3	590
	11th to 20th	Day	9% 6% 33% 33% 15% 3	484
	21st to end	Day	5% 7% 28% 40% 15% 4	531
August	1st to 10th	Day	9% 7% 25% 37% 16% 5%	487
	11th to 20th	Day	7% 6% 21% 39% 18% 8%	477
	21st to end	Day	8% 9% 29% 32% 17% 5%	539
September	1st to 10th	Day	12% 6% 26% 31% 20% 7%	490
	11th to 20th	Day	16% 8% 28% 26% 17% 5%	490
	21st to end	Day	20% 11% 23% 27% 17% 3	490
October	1st to 10th	Day	22% 10% 21% 26% 17% 4	490
	11th to 20th	Day	28% 8% 17% 23% 18% 5%	490
	21st to end	Day	34% 11% 22% 19% 12% 2	539
November	1st to 10th	Day	33% 13% 21% 19% 12% 2	266
	11th to 20th	Day	41% 9% 18% 20% 11% 2	200
	21st to end	Day	36% 10% 17% 25% 12% 2	200
December	1st to 10th	Day	37% 12% 22% 16% 13% 1	200
	11th to 20th	Day	47% 10% 20% 19% 5% 1	200
	21st to end	Day	48% 14% 17% 16% 5%	220
January	1st to 10th	Night	46% 11% 17% 17% 7% 1	800
	11th to 20th	Night	41% 8% 19% 19% 13% 1	800
	21st to end	Night	38% 7% 13% 26% 15% 2	880
February	1st to 10th	Night	39% 8% 16% 26% 11% 1	800
	11th to 20th	Night	36% 10% 16% 23% 13% 1	784
	21st to end	Night	40% 10% 13% 24% 11% 1	660
March	1st to 10th	Night	36% 10% 16% 25% 12% 2	800
	11th to 20th	Night	37% 8% 14% 26% 13% 3	800
	21st to end	Night	42% 9% 14% 21% 11% 2	880
April	1st to 10th	Night	36% 9% 14% 25% 15% 2	800
	11th to 20th	Night	29% 10% 19% 23% 16% 3	734
	21st to end	Night	31% 8% 15% 28% 17% 2	600
May	1st to 10th	Night	25% 7% 15% 33% 15% 4	550
	11th to 20th	Night	29% 7% 12% 27% 22% 3	394
	21st to end	Night	29% 8% 15% 25% 19% 3	422
June	1st to 10th	Night	23% 5% 16% 36% 19% 2	380
	11th to 20th	Night	20% 8% 17% 36% 16% 3	380
	21st to end	Night	20% 6% 13% 34% 25% 2	380
July	1st to 10th	Night	14% 5% 13% 36% 29% 3	370
	11th to 20th	Night	14% 5% 17% 41% 19% 3	368
	21st to end	Night	10% 7% 14% 39% 25% 6%	518
August	1st to 10th	Night	13% 6% 10% 32% 32% 7%	567
	11th to 20th	Night	12% 6% 9% 27% 38% 9%	564
	21st to end	Night	14% 7% 10% 36% 27% 6%	714
September	1st to 10th	Night	13% 4 13% 30% 35% 5%	760
	11th to 20th	Night	16% 4 12% 27% 30% 11%	760
	21st to end	Night	18% 5% 13% 30% 28% 6%	760
October	1st to 10th	Night	21% 6% 14% 26% 28% 5%	760
	11th to 20th	Night	26% 4 10% 28% 24% 8%	760
	21st to end	Night	30% 5% 18% 25% 18% 5%	836
November	1st to 10th	Night	35% 7% 14% 27% 15% 2	780
	11th to 20th	Night	42% 9% 15% 21% 13% 1	800
	21st to end	Night	33% 7% 16% 29% 13% 2	800
December	1st to 10th	Night	33% 9% 18% 24% 14% 2	800
	11th to 20th	Night	45% 8% 16% 22% 9%	800
	21st to end	Night	47% 12% 17% 18% 6%	880

Page generated at 2025-05-23 06:20:59. Version ac07

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