Riverfront Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Riverfront Park clear sky chart from 2005-11-06 to 2026-09-29.

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 7% 4 4 4 4 6% 7% 43%	149204
	Night	13% 8% 3 7% 4 4 4 3 5% 6% 44%	142537
Transparency	Day	40% 5% 12% 25% 17% 2	152800
	Night	41% 4 11% 25% 17% 3	147019
Seeing	Day	18% 13% 29% 25% 12% 3	18284
	Night	19% 13% 30% 27% 11% 1	27984

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	12% 12% 6% 13% 5% 4 3 3 4 6% 33%	4705
	11th to 20th	Day	7% 10% 3 7% 6% 6% 4 3 5% 6% 42%	5310
	21st to end	Day	16% 13% 5% 7% 4 3 3 3 4 5% 37%	5812
February	1st to 10th	Day	15% 12% 4 8% 5% 4 4 3 4 6% 35%	1890
	11th to 20th	Day	15% 10% 3 7% 4 4 4 3 5% 6% 39%	1959
	21st to end	Day	14% 11% 2 8% 4 4 4 3 5% 5% 40%	1730
March	1st to 10th	Day	16% 11% 2 5% 3 3 2 2 4 4 49%	4833
	11th to 20th	Day	9% 6% 2 5% 3 4 3 3 5% 7% 52%	5090
	21st to end	Day	14% 10% 3 8% 5% 5% 5% 4 6% 8% 34%	5765
April	1st to 10th	Day	14% 7% 3 6% 5% 5% 5% 3 4 5% 43%	2520
	11th to 20th	Day	18% 8% 2 6% 3 4 4 3 4 5% 42%	2494
	21st to end	Day	20% 7% 3 6% 5% 4 5% 3 6% 7% 35%	2520
May	1st to 10th	Day	15% 8% 3 7% 5% 5% 5% 4 7% 8% 34%	7197
	11th to 20th	Day	14% 8% 3 7% 4 4 4 4 5% 7% 39%	8163
	21st to end	Day	16% 8% 3 8% 5% 4 5% 4 6% 7% 34%	9047
June	1st to 10th	Day	10% 4 2 5% 4 4 4 5% 7% 9% 46%	2940
	11th to 20th	Day	8% 4 2 4 5% 4 4 5% 6% 10% 48%	2940
	21st to end	Day	6% 4 1 6% 5% 5% 5% 5% 7% 9% 47%	2940
July	1st to 10th	Day	9% 5% 2 6% 4 4 5% 4 6% 10% 45%	8280
	11th to 20th	Day	6% 5% 2 6% 4 5% 5% 4 7% 10% 45%	8203
	21st to end	Day	9% 5% 2 5% 5% 5% 5% 5% 8% 11% 41%	8337
August	1st to 10th	Day	9% 4 2 5% 4 4 5% 4 7% 10% 47%	6014
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 7% 10% 44%	5608
	21st to end	Day	5% 4 1 5% 4 4 4 4 6% 9% 56%	6080
September	1st to 10th	Day	11% 5% 2 5% 3 3 4 3 6% 7% 51%	2520
	11th to 20th	Day	10% 5% 2 4 4 3 5% 3 5% 8% 51%	2520
	21st to end	Day	10% 5% 2 6% 3 3 4 3 5% 7% 51%	2218
October	1st to 10th	Day	10% 4 2 6% 3 4 3 3 4 5% 56%	2000
	11th to 20th	Day	15% 6% 2 5% 3 3 3 2 3 5% 53%	2000
	21st to end	Day	19% 9% 2 5% 4 2 3 2 4 5% 47%	2200
November	1st to 10th	Day	12% 6% 2 5% 4 3 3 3 5% 6% 54%	1902
	11th to 20th	Day	13% 9% 3 6% 3 3 3 3 5% 6% 46%	1890
	21st to end	Day	17% 10% 4 6% 3 3 3 3 4 5% 42%	1729
December	1st to 10th	Day	9% 10% 3 8% 4 3 3 2 4 6% 49%	2690
	11th to 20th	Day	13% 9% 5% 8% 5% 4 3 3 4 6% 40%	3088
	21st to end	Day	21% 19% 5% 11% 5% 4 3 3 4 4 23%	4070
January	1st to 10th	Night	13% 11% 6% 11% 5% 4 3 3 4 4 36%	8214
	11th to 20th	Night	9% 8% 4 11% 5% 5% 5% 4 3 4 40%	7680
	21st to end	Night	16% 13% 4 7% 5% 4 4 3 4 4 36%	8402
February	1st to 10th	Night	15% 11% 4 8% 5% 4 4 4 4 6% 36%	2730
	11th to 20th	Night	16% 8% 3 8% 4 3 3 4 5% 5% 40%	2546
	21st to end	Night	15% 10% 2 7% 4 3 3 3 5% 4 43%	2076
March	1st to 10th	Night	19% 12% 3 5% 3 3 2 2 4 4 43%	5269
	11th to 20th	Night	12% 8% 2 5% 4 3 3 3 5% 6% 49%	5090
	21st to end	Night	17% 9% 3 8% 5% 5% 4 3 5% 6% 34%	5405
April	1st to 10th	Night	12% 7% 3 7% 4 2 3 4 5% 7% 46%	2100
	11th to 20th	Night	14% 8% 2 6% 3 4 3 3 5% 7% 44%	2075
	21st to end	Night	18% 7% 3 5% 4 4 4 3 5% 7% 42%	2100
May	1st to 10th	Night	17% 8% 3 7% 4 4 4 4 6% 8% 36%	5649
	11th to 20th	Night	12% 7% 2 6% 4 4 4 4 6% 9% 43%	4729
	21st to end	Night	16% 8% 3 7% 5% 5% 5% 4 7% 7% 33%	5139
June	1st to 10th	Night	9% 5% 2 5% 4 4 4 3 6% 8% 50%	1680
	11th to 20th	Night	6% 5% 2 6% 4 4 4 4 6% 11% 50%	1680
	21st to end	Night	5% 3 2 4 4 4 4 4 7% 8% 55%	1680
July	1st to 10th	Night	8% 5% 2 7% 5% 4 4 3 6% 8% 47%	4708
	11th to 20th	Night	5% 4 2 6% 4 4 5% 5% 6% 11% 50%	4766
	21st to end	Night	6% 4 2 6% 5% 5% 5% 4 7% 10% 46%	5770
August	1st to 10th	Night	8% 4 2 5% 3 4 3 3 5% 8% 56%	4156
	11th to 20th	Night	11% 4 2 5% 3 4 4 3 6% 8% 50%	4431
	21st to end	Night	5% 3 1 4 3 3 4 3 6% 8% 61%	5046
September	1st to 10th	Night	11% 5% 2 4 3 3 3 2 5% 7% 55%	2100
	11th to 20th	Night	9% 5% 2 5% 3 4 4 4 7% 7% 51%	2100
	21st to end	Night	8% 5% 2 5% 4 4 4 3 5% 5% 55%	2333
October	1st to 10th	Night	8% 4 2 4 3 3 3 3 4 6% 61%	2400
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 5% 6% 52%	2400
	21st to end	Night	18% 7% 2 5% 3 3 3 3 4 4 48%	2640
November	1st to 10th	Night	10% 6% 2 5% 3 3 4 3 4 5% 55%	2616
	11th to 20th	Night	13% 6% 3 5% 3 3 3 3 4 5% 51%	2730
	21st to end	Night	17% 10% 3 6% 3 3 3 3 4 5% 43%	2888
December	1st to 10th	Night	11% 9% 3 6% 4 4 4 3 4 5% 47%	4720
	11th to 20th	Night	16% 9% 3 6% 4 4 4 3 5% 6% 40%	5339
	21st to end	Night	25% 18% 5% 8% 5% 4 3 3 3 4 23%	7150

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	54% 3 10% 21% 9% 2	4706
	11th to 20th	Day	42% 4 10% 23% 16% 4	5310
	21st to end	Day	51% 2 10% 17% 16% 3	5812
February	1st to 10th	Day	52% 4 11% 22% 11% 1	1890
	11th to 20th	Day	48% 4 10% 20% 15% 4	1968
	21st to end	Day	46% 4 8% 23% 15% 4	1730
March	1st to 10th	Day	41% 3 5% 23% 24% 4	4833
	11th to 20th	Day	32% 4 9% 25% 25% 6%	5090
	21st to end	Day	47% 6% 13% 27% 8%	5767
April	1st to 10th	Day	43% 5% 10% 23% 18% 1	2520
	11th to 20th	Day	44% 5% 10% 22% 15% 3	2494
	21st to end	Day	48% 5% 10% 23% 13% 1	2520
May	1st to 10th	Day	46% 6% 12% 22% 14% 1	7232
	11th to 20th	Day	45% 5% 9% 23% 16% 2	8167
	21st to end	Day	49% 5% 10% 20% 16% 1	9061
June	1st to 10th	Day	33% 8% 14% 28% 15% 2	2940
	11th to 20th	Day	30% 7% 13% 27% 19% 4	2940
	21st to end	Day	30% 8% 17% 25% 15% 5%	2940
July	1st to 10th	Day	35% 5% 14% 27% 18% 1	8211
	11th to 20th	Day	34% 6% 16% 26% 17% 2	8128
	21st to end	Day	35% 5% 21% 31% 7% 1	8155
August	1st to 10th	Day	31% 5% 15% 32% 16%	6000
	11th to 20th	Day	35% 6% 16% 29% 13% 1	5645
	21st to end	Day	26% 4 14% 36% 17% 2	6079
September	1st to 10th	Day	32% 5% 10% 26% 22% 4	2520
	11th to 20th	Day	32% 5% 9% 28% 23% 3	2520
	21st to end	Day	33% 6% 9% 26% 24% 3	2218
October	1st to 10th	Day	19% 3 5% 19% 47% 7%	3260
	11th to 20th	Day	24% 2 6% 21% 38% 9%	3240
	21st to end	Day	35% 3 7% 27% 26% 2	3538
November	1st to 10th	Day	33% 4 12% 25% 21% 5%	1902
	11th to 20th	Day	39% 4 8% 25% 20% 4	1890
	21st to end	Day	46% 3 9% 26% 15%	1729
December	1st to 10th	Day	39% 2 13% 30% 15% 1	2690
	11th to 20th	Day	47% 3 11% 24% 14% 1	3085
	21st to end	Day	66% 4 11% 12% 7% 1	4070
January	1st to 10th	Night	53% 3 12% 23% 9%	8215
	11th to 20th	Night	49% 3 6% 24% 15% 3	7680
	21st to end	Night	52% 3 11% 18% 14% 2	8402
February	1st to 10th	Night	50% 5% 11% 20% 13% 2	2730
	11th to 20th	Night	46% 4 9% 21% 16% 3	2547
	21st to end	Night	45% 3 10% 23% 16% 3	2076
March	1st to 10th	Night	46% 3 6% 21% 21% 2	5269
	11th to 20th	Night	37% 4 8% 23% 23% 6%	5090
	21st to end	Night	51% 5% 9% 24% 10% 1	5405
April	1st to 10th	Night	38% 5% 11% 26% 17% 3	2100
	11th to 20th	Night	39% 4 11% 23% 17% 5%	2075
	21st to end	Night	43% 5% 10% 24% 17% 1	2100
May	1st to 10th	Night	47% 6% 13% 22% 12% 1	5679
	11th to 20th	Night	38% 5% 12% 25% 17% 4	4730
	21st to end	Night	48% 6% 12% 18% 15% 1	5149
June	1st to 10th	Night	31% 7% 14% 28% 17% 3	1680
	11th to 20th	Night	29% 6% 11% 28% 24% 3	1680
	21st to end	Night	24% 6% 18% 27% 19% 6%	1680
July	1st to 10th	Night	35% 5% 12% 28% 19% 1	4670
	11th to 20th	Night	29% 6% 15% 30% 19% 2	4721
	21st to end	Night	32% 4 22% 32% 9%	5641
August	1st to 10th	Night	28% 4 15% 33% 20% 1	4146
	11th to 20th	Night	33% 4 14% 32% 15% 2	4459
	21st to end	Night	22% 4 15% 38% 19% 2	5046
September	1st to 10th	Night	30% 5% 10% 25% 25% 5%	2100
	11th to 20th	Night	31% 6% 10% 25% 24% 4	2100
	21st to end	Night	31% 6% 9% 24% 26% 4	2333
October	1st to 10th	Night	16% 3 6% 20% 47% 8%	3920
	11th to 20th	Night	23% 3 7% 23% 34% 11%	3899
	21st to end	Night	34% 3 7% 27% 26% 3	4252
November	1st to 10th	Night	32% 4 12% 26% 20% 6%	2616
	11th to 20th	Night	37% 3 8% 26% 22% 4	2730
	21st to end	Night	44% 3 11% 24% 16% 2	2888
December	1st to 10th	Night	40% 3 9% 33% 14% 1	4720
	11th to 20th	Night	46% 3 11% 22% 17% 1	5341
	21st to end	Night	67% 4 11% 13% 5% 1	7150

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	27% 21% 38% 12% 2	330
	11th to 20th	Day	29% 27% 32% 11% 1	330
	21st to end	Day	22% 26% 40% 11% 1	363
February	1st to 10th	Day	28% 23% 35% 12% 1	330
	11th to 20th	Day	34% 24% 30% 10% 2	330
	21st to end	Day	30% 24% 35% 10% 1	273
March	1st to 10th	Day	25% 26% 40% 8% 1	330
	11th to 20th	Day	32% 24% 32% 11% 1 1	330
	21st to end	Day	33% 21% 34% 11% 1	442
April	1st to 10th	Day	25% 18% 36% 16% 5%	540
	11th to 20th	Day	30% 19% 30% 16% 4	532
	21st to end	Day	26% 18% 35% 16% 5%	540
May	1st to 10th	Day	19% 20% 36% 18% 7% 1	603
	11th to 20th	Day	19% 17% 31% 23% 9% 2	775
	21st to end	Day	16% 13% 32% 26% 10% 4	844
June	1st to 10th	Day	11% 6% 30% 32% 15% 5%	780
	11th to 20th	Day	10% 6% 27% 40% 14% 3	780
	21st to end	Day	9% 7% 34% 34% 14% 3	780
July	1st to 10th	Day	11% 4 18% 33% 26% 9%	771
	11th to 20th	Day	8% 5% 24% 37% 22% 4	768
	21st to end	Day	10% 4 21% 35% 25% 5%	849
August	1st to 10th	Day	10% 4 20% 40% 22% 5%	776
	11th to 20th	Day	11% 3 23% 35% 21% 7%	618
	21st to end	Day	10% 4 20% 32% 28% 7%	627
September	1st to 10th	Day	11% 5% 16% 36% 26% 6%	570
	11th to 20th	Day	11% 3 20% 31% 25% 11%	570
	21st to end	Day	14% 9% 22% 31% 18% 7%	467
October	1st to 10th	Day	11% 11% 32% 27% 15% 4	330
	11th to 20th	Day	22% 19% 31% 19% 8% 1	330
	21st to end	Day	32% 21% 32% 14% 2	363
November	1st to 10th	Day	16% 16% 41% 18% 8% 2	330
	11th to 20th	Day	25% 21% 29% 21% 3 2	330
	21st to end	Day	32% 18% 29% 18% 3	330
December	1st to 10th	Day	21% 23% 34% 15% 6% 1	330
	11th to 20th	Day	24% 21% 35% 17% 3	330
	21st to end	Day	32% 22% 33% 11% 2	363
January	1st to 10th	Night	24% 19% 34% 19% 4	1050
	11th to 20th	Night	25% 23% 32% 17% 3	1050
	21st to end	Night	21% 22% 35% 20% 1	1155
February	1st to 10th	Night	23% 20% 37% 19% 2	1050
	11th to 20th	Night	26% 21% 34% 18% 2	911
	21st to end	Night	26% 20% 35% 17% 1	692
March	1st to 10th	Night	26% 17% 36% 19% 2	746
	11th to 20th	Night	25% 16% 36% 20% 3	630
	21st to end	Night	27% 16% 36% 17% 4	693
April	1st to 10th	Night	20% 20% 35% 21% 3	630
	11th to 20th	Night	21% 16% 35% 23% 5%	623
	21st to end	Night	22% 13% 38% 22% 5%	630
May	1st to 10th	Night	17% 11% 37% 28% 8%	630
	11th to 20th	Night	19% 9% 30% 30% 12% 1	621
	21st to end	Night	15% 6% 29% 32% 17% 2	683
June	1st to 10th	Night	11% 5% 23% 38% 21% 2	630
	11th to 20th	Night	8% 3 28% 42% 17% 1	630
	21st to end	Night	5% 4 29% 41% 19% 1	630
July	1st to 10th	Night	11% 2 13% 38% 31% 5%	615
	11th to 20th	Night	6% 2 19% 40% 30% 3	612
	21st to end	Night	8% 2 17% 41% 31% 2	690
August	1st to 10th	Night	7% 2 14% 47% 29% 2	627
	11th to 20th	Night	8% 3 14% 41% 31% 3	624
	21st to end	Night	8% 1 16% 39% 32% 3	693
September	1st to 10th	Night	13% 3 18% 37% 25% 5%	630
	11th to 20th	Night	11% 3 17% 36% 29% 4	630
	21st to end	Night	11% 8% 23% 32% 22% 4	786
October	1st to 10th	Night	10% 7% 29% 31% 21% 3	800
	11th to 20th	Night	17% 14% 31% 27% 11% 1	800
	21st to end	Night	24% 15% 33% 23% 6%	880
November	1st to 10th	Night	15% 14% 36% 26% 9%	820
	11th to 20th	Night	19% 17% 34% 23% 6%	840
	21st to end	Night	26% 17% 30% 22% 5%	998
December	1st to 10th	Night	23% 18% 33% 21% 4 1	1050
	11th to 20th	Night	26% 14% 33% 24% 4	1050
	21st to end	Night	30% 19% 31% 18% 2	1155

Page generated at 2026-09-26 03:18:45. Version ac07

Copyright © 2026 Attilla Danko.