Seminole Canyon State Park & Historic Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Seminole Canyon State Park & Historic Site clear sky chart from 2005-11-06 to 2024-04-10.

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	9% 4 2 3 3 2 3 4 5% 7% 57%	83667
	Night	8% 4 2 3 3 2 3 4 5% 7% 59%	85185
Transparency	Day	28% 5% 10% 20% 22% 14%	83407
	Night	25% 5% 10% 21% 23% 16%	84968
Seeing	Day	11% 6% 24% 36% 21% 4	13853
	Night	10% 6% 32% 41% 12% 1	24035

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	7% 7% 1 3 3 1 2 2 3 5% 66%	2907
	11th to 20th	Day	7% 5% 1 2 3 2 3 3 3 6% 64%	3170
	21st to end	Day	8% 6% 2 4 4 2 3 4 5% 7% 54%	3487
February	1st to 10th	Day	9% 6% 2 5% 4 2 4 3 4 5% 57%	1900
	11th to 20th	Day	11% 6% 3 3 4 2 3 3 4 6% 56%	1849
	21st to end	Day	9% 5% 2 3 2 1 3 3 5% 7% 59%	1570
March	1st to 10th	Day	12% 6% 2 3 4 2 4 3 5% 5% 54%	3130
	11th to 20th	Day	20% 6% 2 4 4 2 3 4 3 6% 44%	3408
	21st to end	Day	7% 4 2 4 4 2 4 5% 5% 6% 56%	3831
April	1st to 10th	Day	8% 3 2 5% 4 2 4 3 5% 8% 56%	2269
	11th to 20th	Day	11% 4 2 3 3 1 3 3 5% 6% 58%	2131
	21st to end	Day	12% 4 2 3 3 2 3 3 5% 7% 56%	2160
May	1st to 10th	Day	12% 5% 2 3 3 2 3 4 4 8% 52%	2205
	11th to 20th	Day	12% 4 2 3 4 2 3 4 5% 9% 51%	2302
	21st to end	Day	14% 5% 2 4 4 2 4 4 6% 8% 47%	2531
June	1st to 10th	Day	4 2 1 3 3 2 4 4 5% 9% 62%	2340
	11th to 20th	Day	6% 3 2 3 3 2 3 4 5% 8% 61%	2340
	21st to end	Day	6% 3 2 3 4 2 4 5% 6% 10% 56%	2340
July	1st to 10th	Day	11% 3 2 4 4 3 5% 5% 6% 9% 47%	2340
	11th to 20th	Day	5% 2 1 2 3 2 3 4 4 7% 68%	2304
	21st to end	Day	4 2 1 2 3 2 4 4 5% 10% 64%	2349
August	1st to 10th	Day	2 2 1 2 3 2 2 4 4 8% 72%	2149
	11th to 20th	Day	4 3 1 2 4 2 4 5% 5% 10% 59%	2123
	21st to end	Day	6% 3 1 4 4 3 5% 5% 5% 10% 54%	2376
September	1st to 10th	Day	9% 4 2 5% 5% 3 5% 5% 5% 8% 48%	2075
	11th to 20th	Day	11% 6% 2 4 4 3 4 6% 6% 7% 48%	1980
	21st to end	Day	9% 3 1 3 3 3 4 4 6% 6% 57%	1980
October	1st to 10th	Day	7% 3 1 3 4 2 4 3 6% 7% 59%	1980
	11th to 20th	Day	13% 4 2 4 4 2 3 4 4 5% 55%	1980
	21st to end	Day	12% 4 2 4 2 1 2 2 3 5% 64%	2062
November	1st to 10th	Day	13% 4 1 3 3 1 2 2 4 7% 58%	1673
	11th to 20th	Day	9% 4 2 3 3 2 3 4 4 5% 61%	1710
	21st to end	Day	12% 7% 3 3 3 2 3 3 4 6% 54%	1710
December	1st to 10th	Day	14% 6% 2 3 4 1 3 3 5% 5% 53%	1710
	11th to 20th	Day	12% 6% 2 4 3 2 4 4 5% 7% 52%	2161
	21st to end	Day	11% 7% 2 4 2 2 2 2 4 5% 60%	3135
January	1st to 10th	Night	7% 5% 2 3 3 2 2 2 4 7% 63%	4076
	11th to 20th	Night	7% 4 1 2 2 1 2 2 3 4 70%	3800
	21st to end	Night	12% 5% 2 3 3 2 2 3 4 8% 55%	4180
February	1st to 10th	Night	7% 5% 2 4 4 2 3 3 4 7% 60%	2280
	11th to 20th	Night	11% 5% 2 4 3 2 3 3 5% 6% 56%	2218
	21st to end	Night	9% 4 2 3 4 2 3 4 5% 7% 58%	1884
March	1st to 10th	Night	6% 5% 1 3 3 2 4 4 6% 7% 59%	3734
	11th to 20th	Night	17% 6% 2 4 4 2 3 3 5% 5% 49%	3550
	21st to end	Night	7% 5% 2 4 3 2 3 4 5% 6% 60%	3796
April	1st to 10th	Night	6% 4 1 3 3 2 3 4 5% 8% 61%	1900
	11th to 20th	Night	12% 4 1 4 3 2 3 3 5% 5% 58%	1777
	21st to end	Night	11% 3 2 3 3 2 3 3 4 5% 62%	1800
May	1st to 10th	Night	9% 4 2 4 3 3 4 4 5% 7% 56%	1751
	11th to 20th	Night	11% 3 2 4 4 3 3 4 5% 8% 51%	1593
	21st to end	Night	11% 3 2 3 4 3 4 5% 8% 9% 48%	1745
June	1st to 10th	Night	3 2 1 2 3 2 3 4 6% 10% 63%	1620
	11th to 20th	Night	3 2 2 2 3 2 4 4 6% 10% 63%	1620
	21st to end	Night	5% 3 1 3 3 3 4 5% 7% 10% 56%	1620
July	1st to 10th	Night	7% 3 2 5% 4 4 5% 4 6% 11% 49%	1620
	11th to 20th	Night	3 1 1 2 2 3 3 4 5% 8% 67%	1650
	21st to end	Night	4 2 1 2 3 2 3 3 5% 8% 68%	1969
August	1st to 10th	Night	2 1 2 2 1 3 3 4 9% 73%	1790
	11th to 20th	Night	4 2 2 3 4 2 3 4 6% 11% 59%	1778
	21st to end	Night	6% 2 2 3 3 2 5% 5% 7% 11% 55%	1980
September	1st to 10th	Night	6% 4 2 4 4 3 4 5% 5% 8% 55%	1883
	11th to 20th	Night	9% 4 2 4 4 3 4 5% 6% 9% 50%	1980
	21st to end	Night	8% 3 1 3 4 2 4 5% 6% 8% 56%	1980
October	1st to 10th	Night	7% 2 1 3 3 2 4 4 4 6% 63%	1980
	11th to 20th	Night	12% 3 1 3 3 2 3 4 4 6% 59%	1980
	21st to end	Night	8% 2 2 3 2 1 2 2 3 3 70%	2268
November	1st to 10th	Night	12% 3 2 3 2 1 2 2 4 5% 64%	2405
	11th to 20th	Night	7% 3 2 3 3 2 3 4 4 7% 63%	2470
	21st to end	Night	11% 4 1 3 3 2 3 4 5% 6% 58%	2470
December	1st to 10th	Night	11% 5% 2 3 3 2 3 4 5% 7% 56%	2470
	11th to 20th	Night	10% 6% 2 4 4 2 4 4 4 6% 55%	3036
	21st to end	Night	10% 5% 1 3 3 1 3 3 5% 9% 58%	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	23% 2 5% 14% 26% 30%	2908
	11th to 20th	Day	23% 3 6% 18% 27% 22%	3170
	21st to end	Day	30% 4 8% 19% 28% 11%	3487
February	1st to 10th	Day	31% 4 7% 13% 24% 21%	1900
	11th to 20th	Day	32% 3 7% 19% 22% 17%	1859
	21st to end	Day	26% 3 8% 14% 27% 21%	1570
March	1st to 10th	Day	33% 4 7% 14% 21% 22%	3130
	11th to 20th	Day	41% 5% 8% 11% 18% 17%	3408
	21st to end	Day	27% 5% 10% 14% 17% 28%	3831
April	1st to 10th	Day	28% 5% 7% 17% 20% 23%	2269
	11th to 20th	Day	28% 5% 8% 19% 19% 21%	2134
	21st to end	Day	29% 4 7% 20% 20% 20%	2160
May	1st to 10th	Day	30% 6% 9% 17% 23% 15%	2205
	11th to 20th	Day	32% 6% 11% 25% 18% 8%	2306
	21st to end	Day	35% 7% 11% 24% 17% 6%	2531
June	1st to 10th	Day	19% 6% 13% 30% 24% 7%	2340
	11th to 20th	Day	23% 6% 12% 25% 25% 8%	2340
	21st to end	Day	25% 8% 15% 24% 20% 8%	2340
July	1st to 10th	Day	33% 9% 17% 24% 14% 2	2276
	11th to 20th	Day	17% 6% 15% 32% 26% 5%	2235
	21st to end	Day	15% 7% 21% 35% 21% 1	2219
August	1st to 10th	Day	14% 5% 14% 39% 24% 4	2136
	11th to 20th	Day	21% 8% 20% 29% 18% 3	2123
	21st to end	Day	26% 8% 17% 25% 18% 6%	2376
September	1st to 10th	Day	33% 8% 14% 21% 17% 7%	2075
	11th to 20th	Day	35% 8% 12% 20% 21% 4	1980
	21st to end	Day	28% 6% 13% 17% 25% 12%	1980
October	1st to 10th	Day	24% 7% 11% 26% 20% 11%	1980
	11th to 20th	Day	31% 5% 11% 13% 23% 18%	1980
	21st to end	Day	26% 3 5% 15% 29% 22%	2062
November	1st to 10th	Day	28% 4 11% 22% 21% 14%	1673
	11th to 20th	Day	28% 4 9% 19% 22% 18%	1710
	21st to end	Day	34% 4 7% 15% 24% 17%	1710
December	1st to 10th	Day	33% 5% 7% 17% 25% 12%	1710
	11th to 20th	Day	33% 5% 7% 17% 21% 17%	2159
	21st to end	Day	28% 3 5% 16% 26% 22%	3135
January	1st to 10th	Night	21% 3 7% 13% 30% 27%	4076
	11th to 20th	Night	20% 2 5% 18% 26% 29%	3800
	21st to end	Night	30% 4 7% 19% 25% 15%	4180
February	1st to 10th	Night	26% 4 8% 16% 22% 24%	2280
	11th to 20th	Night	30% 4 6% 18% 22% 19%	2218
	21st to end	Night	27% 5% 8% 14% 25% 22%	1884
March	1st to 10th	Night	23% 4 9% 19% 26% 19%	3734
	11th to 20th	Night	37% 5% 8% 14% 19% 17%	3550
	21st to end	Night	25% 5% 11% 18% 15% 25%	3796
April	1st to 10th	Night	23% 5% 11% 19% 19% 23%	1900
	11th to 20th	Night	29% 5% 8% 18% 19% 22%	1777
	21st to end	Night	25% 5% 10% 22% 22% 17%	1800
May	1st to 10th	Night	28% 5% 11% 21% 20% 14%	1751
	11th to 20th	Night	32% 6% 10% 24% 20% 8%	1594
	21st to end	Night	29% 8% 14% 23% 20% 5%	1746
June	1st to 10th	Night	15% 7% 17% 31% 24% 6%	1620
	11th to 20th	Night	17% 7% 15% 27% 23% 10%	1620
	21st to end	Night	23% 6% 14% 25% 22% 9%	1620
July	1st to 10th	Night	30% 8% 18% 25% 17% 2	1575
	11th to 20th	Night	15% 7% 12% 28% 29% 8%	1596
	21st to end	Night	12% 6% 19% 37% 25% 2	1859
August	1st to 10th	Night	11% 5% 14% 34% 31% 5%	1779
	11th to 20th	Night	20% 7% 17% 31% 21% 4	1778
	21st to end	Night	22% 8% 18% 28% 19% 5%	1980
September	1st to 10th	Night	27% 7% 15% 25% 18% 9%	1883
	11th to 20th	Night	29% 8% 16% 22% 19% 5%	1980
	21st to end	Night	25% 7% 13% 24% 18% 14%	1980
October	1st to 10th	Night	23% 6% 12% 25% 21% 13%	1980
	11th to 20th	Night	27% 5% 10% 20% 22% 17%	1980
	21st to end	Night	21% 2 8% 16% 28% 25%	2268
November	1st to 10th	Night	25% 4 8% 21% 27% 16%	2405
	11th to 20th	Night	22% 5% 10% 21% 23% 19%	2470
	21st to end	Night	28% 5% 7% 18% 22% 20%	2470
December	1st to 10th	Night	29% 4 9% 19% 23% 16%	2470
	11th to 20th	Night	31% 5% 7% 17% 21% 19%	3037
	21st to end	Night	25% 4 7% 17% 27% 20%	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	15% 7% 34% 31% 12% 1	270
	11th to 20th	Day	16% 9% 27% 35% 11% 1	270
	21st to end	Day	12% 8% 38% 29% 11% 1	297
February	1st to 10th	Day	14% 10% 29% 31% 14% 2	270
	11th to 20th	Day	20% 10% 32% 29% 8% 1	270
	21st to end	Day	14% 12% 43% 26% 5%	225
March	1st to 10th	Day	19% 7% 43% 24% 7%	270
	11th to 20th	Day	15% 13% 35% 27% 9%	270
	21st to end	Day	10% 15% 43% 26% 5% 1	302
April	1st to 10th	Day	9% 13% 42% 31% 5% 1	457
	11th to 20th	Day	11% 14% 44% 27% 4	412
	21st to end	Day	11% 12% 43% 25% 8%	420
May	1st to 10th	Day	10% 10% 38% 34% 8%	468
	11th to 20th	Day	16% 7% 35% 30% 10% 1	625
	21st to end	Day	16% 7% 34% 36% 7% 1	679
June	1st to 10th	Day	5% 3 23% 50% 17% 2	630
	11th to 20th	Day	6% 1 27% 46% 18% 2	630
	21st to end	Day	7% 2 14% 49% 24% 4	630
July	1st to 10th	Day	9% 1 10% 41% 32% 6%	621
	11th to 20th	Day	3 5% 48% 40% 4	582
	21st to end	Day	2 5% 46% 43% 5%	487
August	1st to 10th	Day	2 1 6% 44% 40% 8%	447
	11th to 20th	Day	6% 1 4 38% 42% 10%	437
	21st to end	Day	5% 1 5% 35% 43% 11%	495
September	1st to 10th	Day	8% 1 7% 34% 41% 9%	365
	11th to 20th	Day	7% 6% 31% 39% 16%	270
	21st to end	Day	11% 1 6% 35% 34% 13%	270
October	1st to 10th	Day	7% 4 17% 40% 30% 2	270
	11th to 20th	Day	14% 3 19% 37% 25% 2	270
	21st to end	Day	17% 7% 23% 30% 21% 3	297
November	1st to 10th	Day	20% 4 23% 34% 19% 2	270
	11th to 20th	Day	16% 10% 15% 34% 17% 7%	270
	21st to end	Day	19% 8% 34% 27% 9% 3	270
December	1st to 10th	Day	15% 4 26% 29% 21% 4	270
	11th to 20th	Day	13% 11% 33% 27% 15% 1	270
	21st to end	Day	18% 8% 24% 31% 18% 1	297
January	1st to 10th	Night	11% 5% 32% 42% 10%	931
	11th to 20th	Night	14% 6% 29% 44% 6%	760
	21st to end	Night	13% 8% 36% 36% 7%	836
February	1st to 10th	Night	11% 8% 39% 35% 7%	760
	11th to 20th	Night	15% 9% 40% 30% 6%	744
	21st to end	Night	10% 11% 47% 32%	628
March	1st to 10th	Night	14% 11% 45% 27% 2	760
	11th to 20th	Night	13% 11% 42% 30% 4	614
	21st to end	Night	10% 12% 53% 22% 4	627
April	1st to 10th	Night	6% 12% 53% 26% 2	570
	11th to 20th	Night	14% 9% 52% 24% 1	533
	21st to end	Night	7% 11% 58% 19% 4	540
May	1st to 10th	Night	8% 9% 54% 27% 2	540
	11th to 20th	Night	10% 6% 43% 34% 6%	531
	21st to end	Night	9% 7% 48% 29% 6%	584
June	1st to 10th	Night	2 3 36% 53% 6%	540
	11th to 20th	Night	4 1 42% 46% 7%	540
	21st to end	Night	5% 2 30% 47% 15% 1	540
July	1st to 10th	Night	9% 2 13% 57% 17% 2	525
	11th to 20th	Night	3 16% 60% 20% 1	522
	21st to end	Night	3 1 12% 63% 21% 1	591
August	1st to 10th	Night	2 1 8% 63% 26% 1	537
	11th to 20th	Night	5% 7% 53% 34% 1	534
	21st to end	Night	6% 8% 54% 31% 2	594
September	1st to 10th	Night	6% 1 9% 51% 30% 3	540
	11th to 20th	Night	9% 1 9% 46% 33% 2	540
	21st to end	Night	8% 16% 43% 31% 1	540
October	1st to 10th	Night	6% 2 24% 51% 17%	540
	11th to 20th	Night	11% 3 27% 47% 11% 1	540
	21st to end	Night	10% 6% 28% 40% 15% 1	684
November	1st to 10th	Night	12% 4 26% 42% 15% 1	925
	11th to 20th	Night	9% 5% 29% 41% 15% 1	950
	21st to end	Night	13% 6% 32% 38% 12%	950
December	1st to 10th	Night	14% 5% 24% 45% 12% 1	950
	11th to 20th	Night	15% 7% 31% 39% 8%	950
	21st to end	Night	13% 5% 34% 41% 7%	1045

Page generated at 2024-04-07 08:28:14. Version ac07

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