Sea Rim State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sea Rim State Park clear sky chart from 2005-11-06 to 2024-11-11.

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% 6% 2 7% 5% 5% 5% 4 7% 9% 38%	100947
	Night	12% 6% 2 6% 4 4 4 4 6% 8% 44%	98273
Transparency	Day	39% 5% 14% 21% 15% 5%	104594
	Night	37% 4 13% 21% 17% 8%	102767
Seeing	Day	12% 4 15% 26% 29% 14%	14847
	Night	13% 5% 18% 29% 28% 8%	24646

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	20% 10% 2 6% 4 3 4 3 4 6% 38%	2847
	11th to 20th	Day	15% 6% 3 4 3 3 3 2 4 5% 53%	2850
	21st to end	Day	23% 9% 3 8% 4 3 4 3 5% 7% 32%	3135
February	1st to 10th	Day	19% 9% 3 7% 6% 3 3 4 5% 6% 35%	1710
	11th to 20th	Day	22% 9% 3 7% 3 3 3 2 4 5% 39%	1950
	21st to end	Day	21% 11% 2 7% 4 3 3 3 4 6% 35%	1727
March	1st to 10th	Day	21% 10% 4 9% 5% 5% 4 4 6% 7% 25%	3436
	11th to 20th	Day	18% 8% 3 8% 6% 5% 5% 4 6% 7% 30%	3480
	21st to end	Day	15% 6% 3 6% 4 4 4 4 5% 6% 43%	3814
April	1st to 10th	Day	14% 8% 3 6% 5% 5% 4 3 6% 8% 38%	2137
	11th to 20th	Day	13% 7% 3 6% 5% 5% 5% 5% 6% 7% 39%	2254
	21st to end	Day	9% 6% 2 6% 5% 4 4 4 5% 9% 46%	2280
May	1st to 10th	Day	16% 8% 3 9% 6% 6% 6% 5% 6% 7% 27%	3765
	11th to 20th	Day	13% 6% 2 6% 3 4 5% 4 6% 8% 43%	3856
	21st to end	Day	7% 5% 2 7% 5% 7% 7% 6% 9% 13% 30%	4477
June	1st to 10th	Day	5% 5% 2 6% 6% 6% 6% 7% 10% 10% 38%	2470
	11th to 20th	Day	5% 4 1 6% 6% 6% 6% 6% 9% 12% 38%	2470
	21st to end	Day	7% 4 2 7% 7% 7% 7% 7% 10% 11% 30%	2470
July	1st to 10th	Day	8% 6% 2 7% 6% 6% 7% 7% 11% 13% 29%	4120
	11th to 20th	Day	6% 6% 3 10% 8% 8% 8% 7% 10% 11% 23%	4120
	21st to end	Day	11% 7% 3 9% 7% 7% 6% 5% 8% 11% 27%	4465
August	1st to 10th	Day	2 2 1 3 3 4 5% 5% 8% 12% 56%	4053
	11th to 20th	Day	3 3 1 4 4 5% 5% 6% 9% 13% 48%	3729
	21st to end	Day	8% 5% 2 8% 6% 6% 7% 6% 7% 9% 37%	4180
September	1st to 10th	Day	9% 6% 3 9% 6% 6% 6% 5% 8% 10% 33%	2238
	11th to 20th	Day	13% 7% 2 7% 5% 5% 5% 4 6% 8% 36%	2090
	21st to end	Day	9% 5% 2 4 4 5% 5% 4 7% 9% 47%	2079
October	1st to 10th	Day	6% 4 2 5% 4 4 4 3 5% 8% 55%	1900
	11th to 20th	Day	11% 3 1 3 3 4 4 3 6% 7% 54%	1900
	21st to end	Day	12% 4 2 4 3 3 3 2 4 6% 55%	2090
November	1st to 10th	Day	11% 6% 3 5% 4 4 4 3 6% 6% 49%	1958
	11th to 20th	Day	12% 5% 2 5% 4 3 4 4 6% 7% 48%	1900
	21st to end	Day	15% 7% 3 6% 4 4 3 3 5% 6% 44%	1900
December	1st to 10th	Day	15% 6% 2 7% 5% 4 3 3 5% 7% 44%	1801
	11th to 20th	Day	14% 8% 3 7% 5% 5% 4 4 5% 6% 40%	2161
	21st to end	Day	16% 8% 2 7% 4 3 4 4 5% 6% 42%	3135
January	1st to 10th	Night	18% 8% 3 7% 4 3 4 3 5% 6% 40%	4108
	11th to 20th	Night	17% 6% 2 6% 3 3 3 3 4 6% 48%	4120
	21st to end	Night	24% 8% 3 6% 4 4 3 3 5% 7% 34%	4532
February	1st to 10th	Night	18% 8% 3 6% 4 5% 3 3 4 6% 39%	2470
	11th to 20th	Night	19% 9% 3 6% 3 3 3 3 4 6% 42%	2129
	21st to end	Night	19% 10% 2 6% 4 4 3 3 6% 7% 37%	1727
March	1st to 10th	Night	23% 13% 3 7% 4 3 3 3 5% 6% 30%	3419
	11th to 20th	Night	21% 9% 3 8% 5% 4 4 4 4 6% 31%	3480
	21st to end	Night	12% 5% 2 6% 4 5% 5% 4 5% 7% 45%	3817
April	1st to 10th	Night	15% 8% 2 6% 4 4 5% 4 5% 7% 40%	2042
	11th to 20th	Night	16% 5% 2 5% 3 4 4 4 6% 7% 45%	1875
	21st to end	Night	11% 5% 2 6% 4 4 4 4 6% 8% 47%	1900
May	1st to 10th	Night	23% 8% 2 7% 4 4 4 4 6% 8% 30%	3130
	11th to 20th	Night	13% 6% 3 6% 4 4 4 4 5% 7% 43%	3024
	21st to end	Night	10% 7% 2 6% 4 4 5% 5% 8% 13% 38%	3090
June	1st to 10th	Night	5% 3 2 4 4 4 3 4 7% 11% 54%	1710
	11th to 20th	Night	5% 4 2 5% 5% 4 5% 4 8% 14% 46%	1710
	21st to end	Night	6% 6% 2 7% 5% 5% 5% 5% 9% 12% 39%	1710
July	1st to 10th	Night	5% 6% 2 7% 5% 4 5% 4 6% 12% 44%	2850
	11th to 20th	Night	2 3 2 7% 6% 6% 9% 6% 10% 12% 38%	2850
	21st to end	Night	6% 6% 3 9% 6% 6% 6% 5% 7% 10% 35%	3098
August	1st to 10th	Night	2 1 1 2 2 3 3 4 6% 10% 66%	2883
	11th to 20th	Night	3 2 1 3 3 3 4 4 8% 14% 57%	3100
	21st to end	Night	6% 3 1 6% 5% 6% 6% 5% 9% 12% 41%	3476
September	1st to 10th	Night	8% 4 2 7% 5% 5% 4 4 7% 11% 43%	1935
	11th to 20th	Night	11% 6% 3 7% 5% 4 4 4 6% 9% 41%	2090
	21st to end	Night	8% 4 2 5% 3 3 4 3 6% 7% 54%	2090
October	1st to 10th	Night	6% 5% 2 4 4 3 3 3 5% 7% 59%	2270
	11th to 20th	Night	9% 4 1 3 3 3 4 3 5% 8% 58%	2280
	21st to end	Night	10% 4 1 3 3 3 2 2 4 6% 60%	2508
November	1st to 10th	Night	9% 6% 2 5% 3 4 4 4 5% 7% 52%	2340
	11th to 20th	Night	13% 5% 1 6% 3 3 3 2 4 6% 53%	2287
	21st to end	Night	12% 6% 3 7% 4 4 4 4 5% 7% 45%	2280
December	1st to 10th	Night	16% 8% 2 7% 4 3 3 3 4 7% 42%	2375
	11th to 20th	Night	15% 9% 2 6% 4 4 4 3 6% 6% 42%	3036
	21st to end	Night	17% 8% 3 7% 4 4 4 3 5% 5% 42%	4532

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	48% 2 4 17% 21% 8%	2848
	11th to 20th	Day	36% 2 5% 26% 22% 9%	2850
	21st to end	Day	54% 2 4 16% 16% 9%	3135
February	1st to 10th	Day	50% 3 6% 15% 16% 9%	1710
	11th to 20th	Day	51% 3 7% 14% 17% 9%	1961
	21st to end	Day	53% 4 7% 14% 15% 7%	1727
March	1st to 10th	Day	60% 3 9% 14% 11% 3	3436
	11th to 20th	Day	54% 3 11% 15% 13% 5%	3480
	21st to end	Day	42% 2 13% 16% 24% 3	3814
April	1st to 10th	Day	43% 4 12% 18% 14% 9%	2137
	11th to 20th	Day	43% 3 12% 19% 15% 8%	2254
	21st to end	Day	33% 4 14% 23% 21% 5%	2280
May	1st to 10th	Day	53% 3 14% 17% 10% 3	3800
	11th to 20th	Day	38% 4 10% 22% 21% 4	3860
	21st to end	Day	41% 5% 16% 30% 8%	4489
June	1st to 10th	Day	31% 6% 21% 27% 14%	2470
	11th to 20th	Day	31% 7% 19% 29% 12% 1	2470
	21st to end	Day	38% 8% 24% 23% 7%	2470
July	1st to 10th	Day	36% 12% 31% 19% 2	4056
	11th to 20th	Day	45% 13% 24% 15% 3	4051
	21st to end	Day	47% 10% 22% 19% 2	4325
August	1st to 10th	Day	17% 6% 20% 44% 13%	4039
	11th to 20th	Day	22% 8% 40% 27% 3	3765
	21st to end	Day	40% 9% 17% 21% 12% 1	4179
September	1st to 10th	Day	40% 10% 19% 17% 13% 3	2238
	11th to 20th	Day	43% 7% 15% 18% 15% 3	2090
	21st to end	Day	32% 5% 15% 24% 15% 9%	2079
October	1st to 10th	Day	21% 3 7% 16% 20% 32%	3160
	11th to 20th	Day	20% 4 6% 24% 37% 10%	3140
	21st to end	Day	25% 3 7% 15% 39% 10%	3428
November	1st to 10th	Day	35% 4 10% 23% 19% 8%	1958
	11th to 20th	Day	34% 4 11% 20% 21% 10%	1900
	21st to end	Day	42% 4 8% 20% 19% 8%	1900
December	1st to 10th	Day	41% 3 11% 23% 15% 7%	1801
	11th to 20th	Day	45% 3 8% 18% 18% 9%	2159
	21st to end	Day	44% 2 7% 17% 22% 8%	3135
January	1st to 10th	Night	48% 2 5% 17% 19% 10%	4108
	11th to 20th	Night	41% 2 3 20% 24% 10%	4120
	21st to end	Night	52% 2 4 16% 17% 9%	4532
February	1st to 10th	Night	47% 3 7% 12% 20% 10%	2470
	11th to 20th	Night	44% 3 7% 17% 18% 10%	2129
	21st to end	Night	46% 4 9% 14% 15% 10%	1727
March	1st to 10th	Night	55% 2 11% 16% 11% 5%	3419
	11th to 20th	Night	55% 4 11% 15% 12% 4	3480
	21st to end	Night	39% 2 12% 15% 24% 7%	3817
April	1st to 10th	Night	43% 4 10% 18% 16% 9%	2042
	11th to 20th	Night	39% 3 11% 21% 15% 11%	1875
	21st to end	Night	35% 4 11% 23% 21% 6%	1900
May	1st to 10th	Night	51% 2 13% 19% 10% 5%	3160
	11th to 20th	Night	40% 4 10% 21% 21% 5%	3025
	21st to end	Night	35% 4 20% 31% 9% 1	3099
June	1st to 10th	Night	24% 5% 20% 35% 15%	1710
	11th to 20th	Night	26% 7% 18% 32% 15% 1	1710
	21st to end	Night	36% 7% 24% 25% 7%	1710
July	1st to 10th	Night	32% 8% 37% 21% 2	2805
	11th to 20th	Night	33% 12% 32% 20% 3	2796
	21st to end	Night	42% 10% 24% 22% 3	2999
August	1st to 10th	Night	14% 5% 20% 44% 16%	2873
	11th to 20th	Night	17% 7% 40% 32% 4	3130
	21st to end	Night	33% 11% 21% 22% 11% 1	3476
September	1st to 10th	Night	35% 8% 21% 19% 13% 3	1935
	11th to 20th	Night	40% 6% 16% 18% 16% 4	2090
	21st to end	Night	30% 5% 13% 23% 20% 8%	2090
October	1st to 10th	Night	21% 4 8% 16% 18% 33%	3790
	11th to 20th	Night	16% 4 6% 26% 31% 17%	3779
	21st to end	Night	19% 2 6% 14% 42% 16%	4120
November	1st to 10th	Night	32% 4 11% 22% 22% 9%	2340
	11th to 20th	Night	34% 3 8% 20% 25% 9%	2287
	21st to end	Night	40% 3 9% 21% 19% 8%	2280
December	1st to 10th	Night	42% 3 10% 22% 15% 8%	2375
	11th to 20th	Night	43% 3 7% 15% 18% 14%	3037
	21st to end	Night	47% 2 6% 15% 22% 8%	4532

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	22% 9% 31% 27% 10%	270
	11th to 20th	Day	16% 9% 31% 31% 11% 1	270
	21st to end	Day	19% 9% 35% 28% 8% 1	297
February	1st to 10th	Day	23% 6% 36% 27% 8%	270
	11th to 20th	Day	27% 10% 30% 28% 6%	270
	21st to end	Day	20% 8% 41% 26% 4	225
March	1st to 10th	Day	18% 6% 38% 30% 7%	270
	11th to 20th	Day	19% 12% 39% 24% 6% 1	270
	21st to end	Day	14% 12% 31% 35% 8% 1	297
April	1st to 10th	Day	13% 11% 32% 33% 11%	317
	11th to 20th	Day	18% 10% 30% 23% 17% 1	452
	21st to end	Day	11% 6% 24% 38% 18% 3	460
May	1st to 10th	Day	13% 7% 25% 33% 19% 3	463
	11th to 20th	Day	10% 4 16% 37% 27% 5%	540
	21st to end	Day	7% 3 15% 38% 31% 6%	734
June	1st to 10th	Day	7% 1 8% 32% 38% 15%	680
	11th to 20th	Day	8% 2 8% 28% 40% 14%	680
	21st to end	Day	10% 2 6% 23% 41% 19%	680
July	1st to 10th	Day	6% 2 5% 17% 43% 26%	671
	11th to 20th	Day	6% 1 1 15% 45% 32%	668
	21st to end	Day	6% 1 3 15% 46% 27%	739
August	1st to 10th	Day	3 1 1 11% 53% 32%	651
	11th to 20th	Day	5% 1 2 8% 42% 42%	479
	21st to end	Day	13% 2 3 14% 35% 34%	539
September	1st to 10th	Day	10% 1 6% 15% 42% 26%	448
	11th to 20th	Day	13% 1 5% 17% 37% 26%	300
	21st to end	Day	12% 1 5% 20% 42% 20%	300
October	1st to 10th	Day	7% 2 7% 32% 38% 14%	300
	11th to 20th	Day	11% 2 10% 32% 34% 11%	300
	21st to end	Day	15% 7% 17% 29% 26% 6%	330
November	1st to 10th	Day	15% 4 16% 32% 29% 5%	300
	11th to 20th	Day	15% 6% 19% 38% 17% 5%	270
	21st to end	Day	17% 7% 30% 29% 15% 3	270
December	1st to 10th	Day	17% 7% 19% 30% 20% 7%	270
	11th to 20th	Day	18% 7% 28% 37% 10%	270
	21st to end	Day	21% 8% 29% 27% 13% 2	297
January	1st to 10th	Night	20% 7% 27% 35% 10%	950
	11th to 20th	Night	19% 7% 27% 36% 10% 1	950
	21st to end	Night	21% 6% 28% 36% 9%	1045
February	1st to 10th	Night	21% 6% 30% 34% 8%	950
	11th to 20th	Night	22% 11% 25% 31% 10%	654
	21st to end	Night	21% 8% 31% 32% 6%	471
March	1st to 10th	Night	19% 7% 29% 32% 12%	570
	11th to 20th	Night	18% 8% 25% 36% 12% 1	570
	21st to end	Night	12% 6% 28% 37% 16% 1	627
April	1st to 10th	Night	17% 8% 24% 37% 14%	570
	11th to 20th	Night	16% 7% 25% 36% 15%	563
	21st to end	Night	12% 5% 27% 37% 18% 1	570
May	1st to 10th	Night	12% 6% 23% 42% 17%	570
	11th to 20th	Night	9% 2 18% 42% 26% 2	561
	21st to end	Night	6% 2 12% 38% 36% 6%	617
June	1st to 10th	Night	5% 1 4 31% 51% 9%	570
	11th to 20th	Night	5% 1 5% 25% 52% 12%	570
	21st to end	Night	6% 1 6% 18% 50% 18%	570
July	1st to 10th	Night	6% 2 4 12% 49% 27%	555
	11th to 20th	Night	3 1 2 9% 48% 38%	552
	21st to end	Night	3 1 3 10% 57% 26%	624
August	1st to 10th	Night	2 1 1 5% 59% 33%	567
	11th to 20th	Night	4 2 7% 54% 32%	564
	21st to end	Night	9% 1 2 15% 50% 23%	627
September	1st to 10th	Night	9% 1 4 13% 48% 24%	570
	11th to 20th	Night	10% 2 4 19% 50% 15%	570
	21st to end	Night	11% 1 6% 22% 48% 13%	570
October	1st to 10th	Night	6% 3 9% 27% 48% 8%	750
	11th to 20th	Night	9% 2 15% 33% 35% 7%	760
	21st to end	Night	12% 5% 14% 35% 30% 4	836
November	1st to 10th	Night	10% 3 17% 34% 31% 5%	780
	11th to 20th	Night	15% 5% 18% 37% 24% 1	763
	21st to end	Night	14% 4 28% 34% 17% 3	760
December	1st to 10th	Night	19% 6% 22% 33% 20% 1	855
	11th to 20th	Night	19% 8% 25% 34% 14%	950
	21st to end	Night	21% 7% 26% 33% 12%	1045

Page generated at 2024-11-08 05:44:50. Version ac07

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