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 2024-11-02.

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 6% 4 4 4 4 6% 7% 43%	101202
	Night	13% 8% 3 6% 4 4 4 3 5% 6% 44%	97816
Transparency	Day	40% 6% 12% 25% 16% 2	100999
	Night	41% 5% 11% 24% 16% 2	97689
Seeing	Day	18% 13% 29% 25% 12% 3	15636
	Night	19% 13% 30% 26% 11% 1	25433

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	11% 13% 6% 11% 4 4 4 4 5% 7% 31%	2527
	11th to 20th	Day	12% 11% 4 7% 7% 7% 4 3 4 5% 34%	2850
	21st to end	Day	20% 16% 7% 6% 4 3 3 3 4 5% 30%	3135
February	1st to 10th	Day	15% 12% 4 8% 5% 4 4 4 4 5% 35%	1710
	11th to 20th	Day	15% 10% 3 6% 4 4 4 3 5% 6% 39%	1767
	21st to end	Day	15% 12% 2 8% 4 4 4 3 5% 5% 39%	1570
March	1st to 10th	Day	18% 11% 3 6% 3 3 3 3 4 5% 42%	3298
	11th to 20th	Day	12% 7% 3 5% 3 4 3 3 4 7% 50%	3480
	21st to end	Day	16% 10% 3 8% 5% 4 4 3 5% 7% 33%	3936
April	1st to 10th	Day	12% 7% 2 6% 5% 5% 5% 3 5% 5% 45%	2280
	11th to 20th	Day	18% 8% 2 6% 3 4 4 3 4 5% 42%	2254
	21st to end	Day	21% 7% 3 6% 5% 4 5% 3 5% 6% 35%	2280
May	1st to 10th	Day	13% 8% 3 7% 5% 5% 5% 5% 7% 9% 33%	3858
	11th to 20th	Day	17% 8% 3 7% 4 4 4 4 5% 6% 38%	4367
	21st to end	Day	11% 6% 2 6% 5% 4 4 3 6% 7% 45%	4824
June	1st to 10th	Day	9% 4 2 5% 4 4 4 5% 7% 10% 47%	2660
	11th to 20th	Day	8% 4 2 4 5% 4 4 4 6% 10% 49%	2660
	21st to end	Day	5% 3 1 5% 5% 5% 5% 5% 7% 9% 48%	2660
July	1st to 10th	Day	13% 6% 2 6% 4 5% 5% 4 6% 10% 40%	4440
	11th to 20th	Day	5% 4 2 5% 4 4 5% 4 7% 10% 50%	4391
	21st to end	Day	8% 5% 2 6% 5% 5% 6% 5% 8% 11% 40%	4465
August	1st to 10th	Day	5% 4 2 5% 4 4 5% 4 8% 10% 49%	4104
	11th to 20th	Day	13% 5% 2 6% 4 4 5% 4 7% 8% 44%	3806
	21st to end	Day	6% 4 2 5% 4 4 4 4 6% 9% 51%	4180
September	1st to 10th	Day	12% 5% 2 5% 3 4 4 3 5% 7% 50%	2280
	11th to 20th	Day	11% 5% 2 4 4 4 4 3 5% 8% 51%	2280
	21st to end	Day	9% 5% 2 6% 3 3 4 3 5% 7% 52%	2026
October	1st to 10th	Day	10% 4 2 6% 3 4 3 3 4 5% 56%	1900
	11th to 20th	Day	15% 6% 2 5% 3 3 2 2 3 5% 53%	1900
	21st to end	Day	18% 9% 2 5% 4 2 3 2 4 4 47%	2090
November	1st to 10th	Day	11% 6% 2 4 3 3 3 3 5% 6% 55%	1728
	11th to 20th	Day	14% 8% 3 6% 3 3 3 3 5% 6% 46%	1710
	21st to end	Day	17% 10% 3 6% 3 3 3 3 4 5% 43%	1565
December	1st to 10th	Day	13% 11% 3 7% 3 4 3 3 4 7% 41%	1520
	11th to 20th	Day	15% 11% 3 7% 4 4 3 3 4 7% 40%	1918
	21st to end	Day	18% 15% 5% 11% 5% 5% 4 4 4 5% 25%	2783
January	1st to 10th	Night	13% 12% 7% 9% 5% 4 3 3 4 4 35%	4424
	11th to 20th	Night	14% 10% 4 12% 6% 7% 6% 4 3 4 30%	4120
	21st to end	Night	23% 17% 5% 7% 3 3 3 3 4 4 29%	4532
February	1st to 10th	Night	15% 11% 4 9% 5% 4 4 4 4 6% 34%	2470
	11th to 20th	Night	15% 8% 3 8% 4 3 3 4 5% 5% 41%	2298
	21st to end	Night	17% 10% 3 8% 4 3 3 3 5% 4 41%	1884
March	1st to 10th	Night	21% 11% 2 5% 3 3 2 2 4 3 44%	3583
	11th to 20th	Night	14% 7% 2 5% 4 3 3 4 4 5% 51%	3480
	21st to end	Night	19% 11% 4 9% 5% 5% 4 3 5% 5% 31%	3694
April	1st to 10th	Night	11% 7% 2 7% 4 2 4 4 5% 7% 47%	1900
	11th to 20th	Night	14% 8% 2 7% 3 4 3 3 5% 7% 45%	1875
	21st to end	Night	19% 6% 3 5% 4 4 4 3 5% 6% 42%	1900
May	1st to 10th	Night	17% 8% 3 6% 3 3 4 4 6% 9% 39%	3024
	11th to 20th	Night	13% 8% 2 6% 5% 5% 4 3 5% 7% 41%	2538
	21st to end	Night	11% 5% 2 6% 4 5% 4 3 7% 8% 44%	2743
June	1st to 10th	Night	8% 4 2 4 4 4 5% 3 6% 8% 51%	1520
	11th to 20th	Night	6% 4 2 5% 4 4 4 4 5% 10% 52%	1520
	21st to end	Night	5% 3 2 4 4 4 4 4 7% 8% 55%	1520
July	1st to 10th	Night	11% 6% 2 6% 5% 4 4 4 6% 8% 44%	2530
	11th to 20th	Night	4 3 1 4 3 3 3 4 6% 10% 58%	2561
	21st to end	Night	6% 5% 2 7% 5% 5% 5% 4 7% 10% 44%	3098
August	1st to 10th	Night	5% 3 1 5% 3 4 3 3 5% 8% 60%	2836
	11th to 20th	Night	12% 5% 2 5% 4 3 3 3 5% 7% 50%	3013
	21st to end	Night	6% 3 1 4 3 3 4 3 6% 8% 58%	3476
September	1st to 10th	Night	12% 5% 2 4 3 3 3 2 5% 7% 55%	1900
	11th to 20th	Night	9% 5% 2 5% 3 4 4 4 6% 6% 52%	1900
	21st to end	Night	8% 4 2 5% 5% 4 4 3 5% 5% 56%	2131
October	1st to 10th	Night	8% 4 2 4 3 3 3 2 4 6% 60%	2280
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 5% 6% 53%	2280
	21st to end	Night	18% 7% 2 5% 3 3 3 3 4 5% 48%	2508
November	1st to 10th	Night	10% 6% 2 5% 3 3 3 3 4 5% 57%	2373
	11th to 20th	Night	13% 7% 3 5% 3 3 3 3 4 5% 50%	2470
	21st to end	Night	17% 10% 2 6% 3 3 3 3 4 5% 45%	2612
December	1st to 10th	Night	14% 11% 3 6% 5% 5% 4 3 5% 6% 37%	2660
	11th to 20th	Night	16% 10% 4 7% 4 4 4 2 5% 5% 40%	3279
	21st to end	Night	19% 20% 6% 9% 5% 5% 3 3 3 4 23%	4884

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	52% 5% 10% 22% 9% 1	2528
	11th to 20th	Day	50% 6% 12% 21% 12%	2850
	21st to end	Day	57% 4 10% 15% 13% 1	3135
February	1st to 10th	Day	53% 4 10% 21% 11% 1	1710
	11th to 20th	Day	47% 4 11% 20% 15% 4	1776
	21st to end	Day	47% 4 9% 21% 14% 4	1570
March	1st to 10th	Day	47% 4 6% 21% 18% 4	3298
	11th to 20th	Day	35% 5% 12% 26% 17% 5%	3480
	21st to end	Day	49% 7% 15% 21% 8% 1	3936
April	1st to 10th	Day	41% 5% 10% 24% 18% 1	2280
	11th to 20th	Day	44% 5% 10% 23% 16% 3	2254
	21st to end	Day	49% 5% 10% 22% 14% 1	2280
May	1st to 10th	Day	45% 9% 13% 21% 12% 1	3893
	11th to 20th	Day	46% 7% 9% 24% 13% 1	4371
	21st to end	Day	37% 7% 10% 23% 21% 1	4837
June	1st to 10th	Day	31% 9% 15% 28% 15% 2	2660
	11th to 20th	Day	29% 8% 12% 28% 19% 4	2660
	21st to end	Day	29% 9% 17% 26% 15% 5%	2660
July	1st to 10th	Day	40% 6% 12% 27% 13% 2	4371
	11th to 20th	Day	28% 6% 14% 33% 17% 2	4316
	21st to end	Day	36% 6% 20% 26% 10% 1	4325
August	1st to 10th	Day	28% 6% 15% 37% 14% 1	4090
	11th to 20th	Day	37% 7% 12% 25% 17% 1	3843
	21st to end	Day	30% 5% 15% 33% 14% 3	4179
September	1st to 10th	Day	33% 5% 11% 24% 22% 4	2280
	11th to 20th	Day	32% 6% 9% 26% 24% 3	2280
	21st to end	Day	31% 6% 9% 27% 24% 3	2026
October	1st to 10th	Day	31% 5% 9% 25% 27% 5%	1900
	11th to 20th	Day	36% 3 8% 24% 24% 5%	1900
	21st to end	Day	42% 3 8% 25% 18% 3	2090
November	1st to 10th	Day	31% 4 13% 24% 22% 5%	1728
	11th to 20th	Day	38% 4 9% 24% 21% 4	1710
	21st to end	Day	44% 4 9% 27% 15%	1565
December	1st to 10th	Day	44% 4 12% 27% 12% 1	1520
	11th to 20th	Day	46% 4 10% 23% 14% 2	1915
	21st to end	Day	61% 5% 9% 14% 9% 1	2783
January	1st to 10th	Night	53% 5% 9% 23% 10% 1	4424
	11th to 20th	Night	58% 4 8% 20% 9% 1	4120
	21st to end	Night	59% 5% 9% 20% 7% 1	4532
February	1st to 10th	Night	51% 5% 10% 19% 13% 2	2470
	11th to 20th	Night	45% 5% 10% 21% 17% 3	2299
	21st to end	Night	47% 3 10% 20% 15% 4	1884
March	1st to 10th	Night	46% 4 8% 23% 17% 3	3583
	11th to 20th	Night	35% 5% 10% 24% 22% 4	3480
	21st to end	Night	54% 7% 9% 24% 6%	3694
April	1st to 10th	Night	36% 5% 11% 26% 18% 4	1900
	11th to 20th	Night	40% 4 10% 23% 17% 5%	1875
	21st to end	Night	44% 5% 9% 23% 18% 1	1900
May	1st to 10th	Night	41% 8% 17% 18% 14% 1	3054
	11th to 20th	Night	41% 8% 12% 26% 12% 1	2539
	21st to end	Night	35% 8% 15% 21% 19% 2	2751
June	1st to 10th	Night	30% 7% 14% 28% 17% 3	1520
	11th to 20th	Night	27% 7% 11% 28% 25% 3	1520
	21st to end	Night	24% 7% 18% 27% 19% 6%	1520
July	1st to 10th	Night	38% 6% 10% 30% 14% 2	2490
	11th to 20th	Night	22% 5% 11% 38% 22% 2	2513
	21st to end	Night	34% 6% 19% 28% 13% 1	2999
August	1st to 10th	Night	22% 4 18% 35% 19% 2	2826
	11th to 20th	Night	34% 5% 13% 27% 19% 3	3041
	21st to end	Night	23% 5% 18% 35% 17% 3	3476
September	1st to 10th	Night	30% 5% 10% 25% 25% 6%	1900
	11th to 20th	Night	31% 6% 10% 23% 26% 4	1900
	21st to end	Night	29% 6% 9% 26% 27% 4	2131
October	1st to 10th	Night	26% 4 10% 26% 29% 5%	2280
	11th to 20th	Night	33% 4 7% 27% 22% 6%	2280
	21st to end	Night	40% 4 8% 22% 22% 4	2508
November	1st to 10th	Night	30% 4 12% 26% 21% 6%	2373
	11th to 20th	Night	37% 3 8% 26% 22% 4	2470
	21st to end	Night	43% 4 11% 24% 17% 2	2612
December	1st to 10th	Night	48% 5% 10% 23% 12% 1	2660
	11th to 20th	Night	47% 4 9% 24% 15% 1	3281
	21st to end	Night	65% 5% 8% 13% 7% 1	4884

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% 22% 37% 11% 2	270
	11th to 20th	Day	34% 24% 31% 11% 1	270
	21st to end	Day	24% 29% 36% 10% 1	297
February	1st to 10th	Day	29% 26% 32% 11% 1	270
	11th to 20th	Day	33% 23% 29% 11% 2	270
	21st to end	Day	32% 24% 35% 7% 1	225
March	1st to 10th	Day	24% 28% 40% 7% 1	270
	11th to 20th	Day	31% 26% 30% 12% 1	270
	21st to end	Day	37% 21% 31% 10% 2	368
April	1st to 10th	Day	22% 19% 38% 16% 5%	460
	11th to 20th	Day	31% 18% 29% 17% 5%	452
	21st to end	Day	28% 18% 35% 14% 5%	460
May	1st to 10th	Day	20% 20% 35% 18% 6% 1	517
	11th to 20th	Day	20% 16% 31% 23% 9% 2	675
	21st to end	Day	15% 14% 32% 25% 11% 4	734
June	1st to 10th	Day	10% 6% 31% 33% 16% 5%	680
	11th to 20th	Day	9% 5% 27% 41% 15% 3	680
	21st to end	Day	8% 7% 37% 32% 13% 2	680
July	1st to 10th	Day	12% 4 19% 32% 25% 8%	671
	11th to 20th	Day	7% 5% 25% 37% 22% 3	668
	21st to end	Day	10% 4 22% 34% 25% 5%	739
August	1st to 10th	Day	10% 4 20% 41% 22% 4	676
	11th to 20th	Day	13% 3 26% 34% 19% 6%	532
	21st to end	Day	11% 3 20% 31% 28% 7%	539
September	1st to 10th	Day	11% 6% 17% 36% 24% 6%	490
	11th to 20th	Day	11% 3 22% 31% 24% 9%	490
	21st to end	Day	12% 10% 23% 33% 17% 5%	403
October	1st to 10th	Day	12% 11% 34% 25% 14% 4	300
	11th to 20th	Day	23% 20% 31% 19% 7%	300
	21st to end	Day	30% 21% 32% 15% 2	330
November	1st to 10th	Day	16% 15% 40% 18% 9% 2	273
	11th to 20th	Day	26% 20% 27% 23% 3 2	270
	21st to end	Day	30% 18% 30% 20% 3	270
December	1st to 10th	Day	21% 23% 34% 14% 7% 1	270
	11th to 20th	Day	26% 20% 33% 18% 3	270
	21st to end	Day	32% 23% 32% 11% 1	297
January	1st to 10th	Night	24% 20% 35% 17% 4	950
	11th to 20th	Night	27% 21% 32% 17% 3	950
	21st to end	Night	23% 22% 34% 20% 1	1045
February	1st to 10th	Night	24% 21% 36% 17% 2	950
	11th to 20th	Night	24% 21% 35% 18% 2	823
	21st to end	Night	29% 20% 35% 15% 2	628
March	1st to 10th	Night	25% 17% 37% 19% 2	675
	11th to 20th	Night	25% 15% 36% 19% 4	570
	21st to end	Night	29% 16% 35% 16% 4	627
April	1st to 10th	Night	20% 21% 35% 20% 4 1	570
	11th to 20th	Night	21% 16% 35% 23% 5%	563
	21st to end	Night	22% 13% 38% 21% 5%	570
May	1st to 10th	Night	16% 12% 37% 26% 8%	570
	11th to 20th	Night	19% 9% 29% 31% 11% 1	561
	21st to end	Night	14% 6% 30% 31% 17% 2	617
June	1st to 10th	Night	10% 5% 24% 37% 22% 2	570
	11th to 20th	Night	8% 3 29% 42% 18% 1	570
	21st to end	Night	5% 4 31% 41% 19% 1	570
July	1st to 10th	Night	12% 3 14% 38% 30% 5%	555
	11th to 20th	Night	5% 2 21% 41% 29% 3	552
	21st to end	Night	8% 2 18% 40% 31% 2	624
August	1st to 10th	Night	7% 2 14% 46% 29% 2	567
	11th to 20th	Night	9% 3 15% 41% 29% 3	564
	21st to end	Night	8% 1 18% 37% 33% 3	627
September	1st to 10th	Night	14% 2 19% 35% 24% 5%	570
	11th to 20th	Night	11% 4 17% 36% 28% 4	570
	21st to end	Night	10% 8% 25% 32% 22% 4	717
October	1st to 10th	Night	10% 7% 30% 29% 21% 3	760
	11th to 20th	Night	17% 14% 32% 26% 10% 1	760
	21st to end	Night	23% 15% 33% 22% 6%	836
November	1st to 10th	Night	14% 14% 37% 25% 10%	745
	11th to 20th	Night	20% 18% 33% 22% 7%	760
	21st to end	Night	25% 17% 32% 21% 5%	902
December	1st to 10th	Night	23% 19% 33% 20% 5% 1	950
	11th to 20th	Night	27% 14% 32% 24% 4	950
	21st to end	Night	29% 21% 31% 17% 2	1045

Page generated at 2024-10-30 00:22:56. Version ac07

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