River Valley RV Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the River Valley RV Park clear sky chart from 2005-11-06 to 2024-02-10.

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	14% 10% 4 7% 7% 4 5% 5% 5% 7% 32%	77900
	Night	15% 11% 4 8% 6% 3 5% 5% 5% 7% 32%	81076
Transparency	Day	51% 7% 12% 19% 11% 1	77601
	Night	52% 6% 12% 19% 10% 1	80896
Seeing	Day	20% 15% 31% 21% 10% 4	14543
	Night	20% 12% 31% 26% 10% 1	24542

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	14% 17% 10% 12% 7% 6% 5% 4 4 4 18%	2527
	11th to 20th	Day	14% 16% 7% 15% 15% 8% 7% 4 3 4 7%	2530
	21st to end	Day	20% 20% 10% 9% 7% 4 5% 4 4 5% 13%	2783
February	1st to 10th	Day	12% 13% 6% 10% 11% 6% 7% 5% 4 6% 21%	1701
	11th to 20th	Day	11% 14% 6% 12% 9% 6% 6% 5% 5% 5% 22%	1726
	21st to end	Day	12% 15% 7% 11% 8% 3 5% 4 5% 6% 23%	1480
March	1st to 10th	Day	12% 11% 5% 8% 8% 5% 6% 4 5% 7% 29%	1800
	11th to 20th	Day	11% 10% 4 7% 7% 4 4 6% 5% 6% 34%	1961
	21st to end	Day	16% 11% 4 7% 6% 3 5% 4 5% 6% 32%	2202
April	1st to 10th	Day	18% 13% 5% 8% 6% 3 4 4 5% 7% 29%	2160
	11th to 20th	Day	18% 11% 3 5% 6% 3 5% 4 4 5% 36%	2244
	21st to end	Day	15% 9% 4 7% 7% 4 6% 4 5% 6% 34%	2340
May	1st to 10th	Day	17% 7% 3 5% 6% 4 5% 5% 7% 7% 34%	2340
	11th to 20th	Day	16% 6% 3 5% 6% 3 5% 6% 6% 7% 38%	2301
	21st to end	Day	10% 6% 3 5% 5% 4 6% 5% 6% 8% 42%	2707
June	1st to 10th	Day	12% 5% 3 5% 6% 3 5% 5% 6% 8% 42%	2564
	11th to 20th	Day	12% 5% 3 5% 5% 3 4 6% 6% 8% 42%	2700
	21st to end	Day	10% 6% 3 6% 6% 3 6% 6% 6% 8% 41%	2540
July	1st to 10th	Day	6% 4 2 5% 5% 4 5% 5% 7% 10% 49%	2520
	11th to 20th	Day	7% 6% 2 5% 6% 4 5% 5% 6% 9% 45%	2520
	21st to end	Day	7% 4 2 5% 7% 4 7% 6% 7% 10% 41%	2743
August	1st to 10th	Day	8% 5% 2 6% 6% 5% 6% 7% 6% 9% 41%	2332
	11th to 20th	Day	9% 5% 3 5% 5% 3 5% 5% 6% 10% 43%	2303
	21st to end	Day	11% 6% 2 5% 5% 3 4 5% 6% 9% 43%	2499
September	1st to 10th	Day	11% 6% 3 5% 5% 4 6% 6% 5% 9% 41%	2098
	11th to 20th	Day	12% 5% 2 5% 5% 3 4 5% 6% 8% 45%	1980
	21st to end	Day	14% 6% 3 6% 6% 4 5% 5% 5% 9% 38%	1980
October	1st to 10th	Day	16% 7% 3 7% 6% 3 4 4 4 6% 40%	1972
	11th to 20th	Day	21% 9% 4 8% 7% 4 5% 5% 5% 7% 25%	1751
	21st to end	Day	21% 12% 4 7% 7% 4 4 5% 5% 7% 23%	1782
November	1st to 10th	Day	13% 10% 4 8% 5% 4 5% 5% 6% 7% 34%	1672
	11th to 20th	Day	13% 14% 6% 9% 7% 4 5% 5% 5% 7% 24%	1710
	21st to end	Day	20% 17% 5% 9% 8% 3 5% 3 3 4 22%	1634
December	1st to 10th	Day	16% 14% 7% 14% 7% 4 5% 4 4 6% 18%	1392
	11th to 20th	Day	15% 16% 5% 10% 8% 4 4 6% 5% 6% 21%	1675
	21st to end	Day	26% 21% 8% 10% 7% 3 5% 4 3 4 10%	2731
January	1st to 10th	Night	16% 15% 7% 11% 8% 4 5% 4 5% 5% 21%	4428
	11th to 20th	Night	13% 14% 7% 14% 12% 9% 6% 4 4 4 12%	4440
	21st to end	Night	18% 19% 8% 12% 8% 3 5% 5% 5% 5% 13%	4884
February	1st to 10th	Night	12% 12% 5% 10% 9% 5% 6% 6% 6% 6% 23%	2464
	11th to 20th	Night	13% 13% 6% 9% 7% 5% 6% 5% 5% 6% 26%	2116
	21st to end	Night	16% 13% 5% 11% 8% 3 5% 4 4 5% 26%	1776
March	1st to 10th	Night	14% 9% 4 7% 6% 3 5% 3 5% 6% 37%	2160
	11th to 20th	Night	13% 7% 3 6% 5% 4 4 5% 5% 7% 39%	1999
	21st to end	Night	17% 9% 4 7% 6% 3 4 4 4 6% 36%	2170
April	1st to 10th	Night	16% 11% 3 6% 4 3 5% 5% 4 8% 35%	1800
	11th to 20th	Night	18% 7% 3 6% 4 2 4 4 5% 7% 39%	1663
	21st to end	Night	17% 9% 3 5% 4 3 4 5% 5% 7% 38%	1620
May	1st to 10th	Night	13% 7% 3 6% 6% 3 6% 5% 6% 8% 37%	1620
	11th to 20th	Night	15% 6% 3 7% 5% 3 5% 5% 5% 8% 40%	1592
	21st to end	Night	12% 6% 2 4 4 2 4 5% 5% 9% 47%	1566
June	1st to 10th	Night	13% 5% 2 4 4 3 5% 5% 5% 7% 46%	1386
	11th to 20th	Night	10% 6% 3 4 5% 2 5% 5% 6% 9% 45%	1260
	21st to end	Night	8% 6% 3 5% 4 3 4 6% 6% 8% 48%	1408
July	1st to 10th	Night	6% 3 2 4 3 3 3 5% 6% 9% 56%	1440
	11th to 20th	Night	6% 4 2 5% 5% 3 5% 5% 5% 8% 53%	1440
	21st to end	Night	7% 5% 2 4 3 2 5% 5% 6% 9% 52%	1575
August	1st to 10th	Night	7% 4 1 4 4 3 4 6% 7% 11% 49%	1606
	11th to 20th	Night	7% 4 2 4 4 3 5% 4 7% 9% 52%	1598
	21st to end	Night	10% 5% 2 4 4 2 4 4 5% 8% 51%	1854
September	1st to 10th	Night	9% 4 2 5% 5% 2 5% 5% 6% 7% 50%	1843
	11th to 20th	Night	11% 4 2 4 4 2 3 4 5% 7% 54%	1980
	21st to end	Night	13% 6% 3 5% 4 3 5% 5% 6% 8% 42%	1980
October	1st to 10th	Night	18% 6% 2 5% 4 2 4 4 5% 7% 44%	1988
	11th to 20th	Night	18% 10% 3 8% 7% 3 4 4 4 5% 34%	2206
	21st to end	Night	23% 10% 3 6% 5% 3 5% 5% 5% 7% 29%	2574
November	1st to 10th	Night	12% 9% 3 6% 6% 3 4 4 6% 7% 39%	2406
	11th to 20th	Night	14% 11% 5% 8% 7% 4 5% 5% 6% 7% 27%	2470
	21st to end	Night	17% 14% 6% 8% 8% 4 4 5% 5% 6% 23%	2542
December	1st to 10th	Night	16% 15% 7% 10% 8% 4 6% 5% 4 5% 20%	2784
	11th to 20th	Night	14% 14% 6% 11% 8% 4 5% 5% 6% 7% 19%	3522
	21st to end	Night	27% 20% 6% 10% 6% 3 4 3 3 4 13%	4916

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	68% 8% 12% 8% 3	2528
	11th to 20th	Day	81% 6% 6% 5% 1	2530
	21st to end	Day	74% 6% 11% 6% 3	2783
February	1st to 10th	Day	62% 7% 9% 16% 5%	1701
	11th to 20th	Day	63% 6% 9% 13% 8% 1	1736
	21st to end	Day	62% 6% 10% 14% 6% 1	1480
March	1st to 10th	Day	55% 5% 12% 18% 9% 1	1800
	11th to 20th	Day	50% 6% 11% 18% 12% 3	1961
	21st to end	Day	53% 7% 10% 18% 10% 1	2202
April	1st to 10th	Day	56% 5% 11% 17% 11%	2160
	11th to 20th	Day	50% 5% 10% 18% 15% 2	2244
	21st to end	Day	51% 7% 12% 14% 14% 2	2340
May	1st to 10th	Day	47% 8% 11% 21% 12% 2	2340
	11th to 20th	Day	45% 6% 12% 22% 14% 2	2305
	21st to end	Day	38% 8% 14% 25% 14% 1	2707
June	1st to 10th	Day	39% 7% 13% 25% 15% 1	2564
	11th to 20th	Day	38% 7% 12% 23% 18% 1	2700
	21st to end	Day	39% 9% 13% 24% 14% 1	2540
July	1st to 10th	Day	30% 8% 14% 27% 18% 3	2451
	11th to 20th	Day	34% 8% 12% 26% 18% 1	2445
	21st to end	Day	35% 9% 14% 22% 17% 2	2591
August	1st to 10th	Day	38% 9% 13% 25% 13% 2	2318
	11th to 20th	Day	36% 8% 15% 25% 15% 2	2303
	21st to end	Day	38% 7% 14% 25% 15% 2	2499
September	1st to 10th	Day	40% 8% 13% 25% 12% 2	2098
	11th to 20th	Day	36% 7% 15% 28% 13% 1	1980
	21st to end	Day	43% 7% 14% 25% 10%	1980
October	1st to 10th	Day	46% 6% 10% 25% 12% 1	1972
	11th to 20th	Day	58% 7% 11% 17% 6%	1751
	21st to end	Day	60% 7% 13% 14% 6%	1782
November	1st to 10th	Day	49% 8% 13% 20% 10%	1672
	11th to 20th	Day	59% 7% 14% 14% 6% 1	1710
	21st to end	Day	66% 7% 12% 11% 5%	1634
December	1st to 10th	Day	68% 6% 10% 13% 2	1392
	11th to 20th	Day	64% 7% 13% 13% 3	1671
	21st to end	Day	79% 5% 8% 5% 3	2731
January	1st to 10th	Night	64% 6% 10% 13% 6% 1	4428
	11th to 20th	Night	75% 6% 8% 8% 3	4440
	21st to end	Night	70% 9% 10% 7% 3	4884
February	1st to 10th	Night	60% 7% 9% 16% 7% 1	2464
	11th to 20th	Night	59% 6% 11% 17% 7% 1	2117
	21st to end	Night	61% 4 11% 15% 8% 1	1776
March	1st to 10th	Night	49% 5% 13% 22% 11% 1	2160
	11th to 20th	Night	44% 6% 11% 22% 14% 2	1999
	21st to end	Night	50% 6% 11% 19% 12% 2	2170
April	1st to 10th	Night	49% 5% 10% 20% 14% 1	1800
	11th to 20th	Night	45% 4 10% 21% 18% 2	1663
	21st to end	Night	44% 6% 11% 21% 14% 3	1620
May	1st to 10th	Night	44% 6% 12% 21% 13% 3	1620
	11th to 20th	Night	43% 6% 9% 23% 16% 3	1593
	21st to end	Night	35% 7% 13% 28% 15% 3	1567
June	1st to 10th	Night	36% 7% 10% 27% 18% 2	1386
	11th to 20th	Night	35% 8% 13% 22% 21% 1	1260
	21st to end	Night	33% 8% 13% 27% 17% 2	1408
July	1st to 10th	Night	23% 7% 14% 32% 21% 4	1400
	11th to 20th	Night	28% 5% 16% 30% 18% 1	1392
	21st to end	Night	30% 8% 16% 27% 18% 2	1487
August	1st to 10th	Night	28% 8% 19% 31% 13% 1	1596
	11th to 20th	Night	28% 7% 15% 32% 16% 1	1598
	21st to end	Night	31% 7% 13% 28% 19% 1	1854
September	1st to 10th	Night	33% 7% 13% 28% 18% 1	1843
	11th to 20th	Night	30% 6% 13% 37% 13% 1	1980
	21st to end	Night	39% 7% 14% 29% 9% 1	1980
October	1st to 10th	Night	39% 7% 12% 26% 14% 1	1988
	11th to 20th	Night	52% 5% 12% 22% 7% 1	2206
	21st to end	Night	55% 6% 12% 18% 8%	2574
November	1st to 10th	Night	43% 7% 14% 23% 12% 1	2406
	11th to 20th	Night	54% 8% 14% 17% 7% 1	2470
	21st to end	Night	61% 7% 14% 14% 4	2542
December	1st to 10th	Night	66% 6% 10% 13% 5%	2784
	11th to 20th	Night	63% 7% 14% 10% 6% 1	3525
	21st to end	Night	76% 5% 8% 7% 3	4916

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	26% 20% 38% 11% 5%	270
	11th to 20th	Day	28% 20% 40% 9% 4	270
	21st to end	Day	29% 15% 36% 14% 5%	297
February	1st to 10th	Day	24% 28% 33% 11% 2 1	267
	11th to 20th	Day	27% 29% 35% 8% 1	240
	21st to end	Day	38% 28% 29% 4 1	198
March	1st to 10th	Day	29% 31% 32% 8% 1	240
	11th to 20th	Day	23% 19% 33% 17% 6%	401
	21st to end	Day	29% 16% 31% 17% 5% 1	462
April	1st to 10th	Day	27% 17% 32% 16% 6% 1	420
	11th to 20th	Day	33% 16% 26% 15% 8% 2	412
	21st to end	Day	23% 18% 30% 21% 6% 2	420
May	1st to 10th	Day	25% 17% 33% 15% 6% 4	423
	11th to 20th	Day	20% 14% 31% 21% 8% 5%	447
	21st to end	Day	15% 14% 30% 25% 12% 3	661
June	1st to 10th	Day	14% 15% 33% 28% 8% 3	630
	11th to 20th	Day	15% 14% 36% 22% 10% 4	630
	21st to end	Day	13% 14% 35% 25% 11% 3	630
July	1st to 10th	Day	7% 7% 32% 29% 17% 7%	621
	11th to 20th	Day	9% 11% 31% 30% 14% 6%	618
	21st to end	Day	9% 9% 34% 27% 16% 6%	684
August	1st to 10th	Day	9% 7% 25% 28% 19% 12%	451
	11th to 20th	Day	10% 6% 22% 33% 16% 13%	439
	21st to end	Day	15% 10% 23% 29% 16% 6%	495
September	1st to 10th	Day	14% 10% 30% 23% 14% 9%	450
	11th to 20th	Day	14% 9% 23% 28% 20% 6%	450
	21st to end	Day	22% 12% 23% 22% 16% 6%	450
October	1st to 10th	Day	24% 13% 26% 21% 14% 2	450
	11th to 20th	Day	29% 13% 34% 18% 4	401
	21st to end	Day	31% 21% 33% 11% 4 1	297
November	1st to 10th	Day	26% 19% 36% 14% 5%	270
	11th to 20th	Day	25% 26% 35% 11% 3 1	270
	21st to end	Day	26% 27% 33% 10% 3	234
December	1st to 10th	Day	29% 25% 30% 10% 5% 1	180
	11th to 20th	Day	32% 22% 37% 9% 1	180
	21st to end	Day	33% 27% 29% 8% 2	285
January	1st to 10th	Night	24% 19% 33% 19% 5% 1	950
	11th to 20th	Night	25% 18% 32% 19% 5% 1	950
	21st to end	Night	20% 12% 36% 25% 6%	1045
February	1st to 10th	Night	19% 18% 35% 23% 4	759
	11th to 20th	Night	23% 19% 33% 20% 4	703
	21st to end	Night	27% 19% 33% 18% 3	592
March	1st to 10th	Night	19% 16% 34% 23% 8%	720
	11th to 20th	Night	19% 20% 32% 23% 6%	720
	21st to end	Night	22% 16% 33% 24% 5% 1	784
April	1st to 10th	Night	21% 14% 36% 22% 6% 1	540
	11th to 20th	Night	22% 14% 31% 25% 6% 2	533
	21st to end	Night	21% 11% 31% 28% 7% 1	540
May	1st to 10th	Night	15% 11% 37% 29% 7% 1	540
	11th to 20th	Night	18% 8% 28% 32% 12% 1	531
	21st to end	Night	16% 7% 28% 30% 17% 2	584
June	1st to 10th	Night	14% 8% 29% 34% 14% 1	486
	11th to 20th	Night	14% 8% 29% 35% 13% 1	360
	21st to end	Night	11% 5% 28% 39% 15% 1	508
July	1st to 10th	Night	8% 3 21% 41% 23% 3	525
	11th to 20th	Night	8% 3 23% 41% 23% 3	522
	21st to end	Night	8% 4 28% 39% 20% 1	591
August	1st to 10th	Night	9% 2 24% 39% 26% 1	537
	11th to 20th	Night	9% 4 20% 37% 26% 3	534
	21st to end	Night	12% 4 23% 36% 23% 2	594
September	1st to 10th	Night	10% 6% 27% 31% 21% 4	583
	11th to 20th	Night	13% 5% 24% 33% 22% 4	720
	21st to end	Night	17% 9% 24% 27% 19% 3	720
October	1st to 10th	Night	21% 9% 26% 28% 16% 1	720
	11th to 20th	Night	23% 15% 31% 23% 7% 1	720
	21st to end	Night	30% 14% 30% 20% 5% 1	792
November	1st to 10th	Night	20% 14% 34% 22% 10% 1	740
	11th to 20th	Night	23% 18% 33% 20% 5% 1	760
	21st to end	Night	26% 16% 33% 21% 5%	760
December	1st to 10th	Night	26% 17% 32% 21% 4	884
	11th to 20th	Night	25% 18% 35% 17% 4 1	950
	21st to end	Night	32% 15% 32% 19% 2	1045

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