Mequon Rotary Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mequon Rotary Park clear sky chart from 2005-11-06 to 2026-10-14.

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% 8% 3 7% 5% 5% 5% 4 6% 8% 38%	149553
	Night	13% 9% 3 8% 5% 4 4 4 5% 7% 38%	142521
Transparency	Day	44% 2 12% 27% 14% 2	153040
	Night	47% 2 11% 25% 15% 2	147098
Seeing	Day	15% 6% 24% 32% 18% 4	18611
	Night	18% 7% 26% 29% 16% 3	28371

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% 12% 5% 12% 6% 5% 5% 5% 6% 7% 26%	4691
	11th to 20th	Day	8% 10% 5% 10% 5% 4 6% 5% 8% 7% 32%	4710
	21st to end	Day	10% 12% 6% 9% 5% 6% 5% 3 5% 8% 31%	5156
February	1st to 10th	Day	10% 13% 6% 10% 5% 5% 5% 4 5% 7% 29%	1890
	11th to 20th	Day	12% 11% 4 8% 5% 5% 5% 4 5% 6% 36%	2048
	21st to end	Day	12% 12% 5% 10% 5% 5% 5% 4 6% 5% 32%	1730
March	1st to 10th	Day	13% 8% 3 7% 5% 3 4 3 5% 6% 43%	4580
	11th to 20th	Day	11% 6% 2 7% 6% 5% 5% 4 5% 6% 42%	4769
	21st to end	Day	19% 11% 5% 10% 5% 5% 4 3 5% 5% 28%	6099
April	1st to 10th	Day	17% 11% 3 7% 5% 4 5% 4 5% 7% 31%	2520
	11th to 20th	Day	15% 9% 3 8% 6% 6% 4 4 6% 6% 35%	2494
	21st to end	Day	16% 9% 3 6% 5% 5% 5% 4 6% 6% 34%	2677
May	1st to 10th	Day	12% 7% 3 7% 5% 5% 5% 4 6% 7% 39%	7616
	11th to 20th	Day	12% 7% 2 7% 5% 5% 6% 4 6% 7% 38%	8212
	21st to end	Day	14% 6% 2 5% 4 4 5% 4 6% 8% 41%	9047
June	1st to 10th	Day	10% 6% 2 6% 5% 5% 5% 4 6% 9% 43%	2940
	11th to 20th	Day	10% 6% 2 7% 5% 4 5% 4 7% 8% 42%	2940
	21st to end	Day	9% 5% 2 6% 5% 4 6% 4 8% 8% 43%	2940
July	1st to 10th	Day	9% 7% 3 7% 4 5% 5% 4 7% 9% 40%	8280
	11th to 20th	Day	4 4 2 5% 4 4 5% 4 8% 11% 49%	8280
	21st to end	Day	7% 5% 2 6% 4 5% 5% 4 6% 9% 47%	8990
August	1st to 10th	Day	12% 5% 2 5% 4 4 5% 5% 7% 8% 43%	6441
	11th to 20th	Day	13% 5% 2 6% 4 4 5% 3 6% 8% 43%	5652
	21st to end	Day	8% 6% 2 6% 4 4 5% 4 6% 9% 46%	6080
September	1st to 10th	Day	10% 5% 2 6% 4 4 5% 4 7% 7% 45%	2520
	11th to 20th	Day	12% 5% 2 5% 4 4 4 4 4 8% 49%	2386
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 3 6% 9% 41%	2310
October	1st to 10th	Day	13% 6% 2 6% 3 3 4 4 5% 7% 48%	2246
	11th to 20th	Day	18% 8% 3 8% 5% 5% 5% 4 6% 6% 32%	1985
	21st to end	Day	15% 8% 2 8% 6% 5% 4 4 4 6% 38%	1980
November	1st to 10th	Day	12% 8% 3 8% 5% 4 4 3 5% 7% 42%	1852
	11th to 20th	Day	11% 11% 3 9% 7% 6% 5% 4 6% 7% 30%	1890
	21st to end	Day	17% 12% 3 7% 5% 4 3 3 4 6% 36%	1754
December	1st to 10th	Day	10% 10% 4 8% 6% 6% 5% 3 6% 7% 35%	2690
	11th to 20th	Day	13% 14% 4 9% 6% 7% 6% 5% 7% 6% 24%	3088
	21st to end	Day	22% 19% 7% 11% 5% 4 4 4 3 5% 16%	4070
January	1st to 10th	Night	13% 12% 6% 12% 5% 4 4 3 4 5% 32%	8232
	11th to 20th	Night	10% 13% 6% 12% 6% 6% 6% 5% 7% 5% 22%	8280
	21st to end	Night	10% 14% 4 10% 6% 5% 5% 4 6% 7% 30%	9058
February	1st to 10th	Night	13% 14% 5% 8% 5% 4 4 4 6% 5% 32%	2724
	11th to 20th	Night	12% 11% 3 7% 5% 4 5% 4 4 5% 39%	2458
	21st to end	Night	18% 12% 3 7% 3 4 4 3 5% 6% 36%	2076
March	1st to 10th	Night	16% 7% 3 6% 3 4 4 4 4 6% 43%	5493
	11th to 20th	Night	11% 6% 2 6% 4 4 5% 4 6% 9% 45%	5438
	21st to end	Night	17% 11% 5% 10% 6% 5% 4 3 4 5% 30%	5072
April	1st to 10th	Night	17% 10% 3 6% 5% 4 5% 4 5% 6% 37%	2100
	11th to 20th	Night	20% 9% 3 6% 4 4 4 3 4 5% 38%	2075
	21st to end	Night	17% 8% 2 5% 4 4 4 3 5% 7% 40%	1943
May	1st to 10th	Night	13% 7% 3 6% 5% 5% 4 4 6% 8% 40%	5237
	11th to 20th	Night	10% 8% 4 7% 4 4 5% 4 6% 7% 40%	4675
	21st to end	Night	15% 7% 2 6% 5% 4 4 3 4 6% 43%	5139
June	1st to 10th	Night	11% 4 2 6% 5% 4 6% 5% 5% 7% 46%	1680
	11th to 20th	Night	13% 6% 3 5% 4 3 5% 4 6% 9% 42%	1680
	21st to end	Night	9% 7% 3 6% 5% 4 4 3 5% 8% 45%	1680
July	1st to 10th	Night	11% 7% 3 6% 4 4 4 4 6% 8% 43%	4708
	11th to 20th	Night	4 4 2 5% 4 3 4 4 6% 9% 56%	4707
	21st to end	Night	6% 4 2 6% 4 4 5% 4 6% 9% 50%	5117
August	1st to 10th	Night	15% 6% 3 5% 3 3 4 3 6% 8% 43%	3726
	11th to 20th	Night	10% 6% 3 7% 4 4 4 4 6% 9% 43%	4377
	21st to end	Night	7% 4 2 5% 4 4 5% 4 6% 10% 48%	5046
September	1st to 10th	Night	9% 4 2 6% 4 4 5% 3 6% 8% 50%	2100
	11th to 20th	Night	11% 4 1 5% 4 3 4 3 5% 7% 52%	2212
	21st to end	Night	13% 6% 2 7% 4 4 4 3 5% 6% 45%	2310
October	1st to 10th	Night	14% 6% 2 6% 3 4 4 2 5% 7% 48%	2371
	11th to 20th	Night	18% 7% 2 6% 4 3 3 3 5% 6% 41%	2481
	21st to end	Night	19% 9% 3 7% 4 4 4 3 5% 8% 35%	2860
November	1st to 10th	Night	12% 8% 3 7% 5% 3 4 3 4 7% 44%	2666
	11th to 20th	Night	14% 11% 3 8% 5% 4 6% 3 5% 6% 35%	2730
	21st to end	Night	16% 10% 4 7% 5% 5% 5% 3 5% 6% 34%	2861
December	1st to 10th	Night	11% 11% 3 8% 4 4 5% 3 5% 6% 40%	4720
	11th to 20th	Night	16% 17% 5% 9% 5% 5% 4 3 5% 5% 26%	5339
	21st to end	Night	21% 18% 5% 11% 5% 5% 4 3 4 5% 18%	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	59% 2 15% 18% 6%	4692
	11th to 20th	Day	51% 2 9% 23% 14% 1	4710
	21st to end	Day	54% 1 7% 24% 13%	5156
February	1st to 10th	Day	55% 3 11% 20% 9% 1	1890
	11th to 20th	Day	50% 2 11% 25% 11% 2	2058
	21st to end	Day	54% 3 11% 20% 11% 2	1730
March	1st to 10th	Day	43% 2 12% 26% 12% 6%	4580
	11th to 20th	Day	44% 1 13% 26% 14% 2	4769
	21st to end	Day	59% 2 12% 16% 10% 1	6101
April	1st to 10th	Day	52% 4 11% 21% 11% 1	2520
	11th to 20th	Day	49% 3 10% 22% 13% 3	2494
	21st to end	Day	49% 4 13% 21% 11% 2	2677
May	1st to 10th	Day	44% 2 8% 30% 14% 2	7651
	11th to 20th	Day	46% 1 9% 27% 15% 1	8216
	21st to end	Day	41% 2 9% 26% 18% 4	9061
June	1st to 10th	Day	39% 3 12% 27% 17% 3	2940
	11th to 20th	Day	39% 3 14% 25% 18% 1	2940
	21st to end	Day	37% 4 15% 26% 16% 2	2940
July	1st to 10th	Day	41% 3 12% 30% 12% 2	8211
	11th to 20th	Day	29% 2 14% 35% 19% 1	8205
	21st to end	Day	35% 3 13% 26% 21% 2	8794
August	1st to 10th	Day	39% 2 15% 31% 12% 1	6426
	11th to 20th	Day	39% 3 16% 33% 9%	5691
	21st to end	Day	36% 2 14% 33% 14% 1	6079
September	1st to 10th	Day	37% 4 11% 31% 14% 2	2520
	11th to 20th	Day	34% 3 12% 34% 16% 1	2386
	21st to end	Day	40% 3 11% 32% 14%	2310
October	1st to 10th	Day	24% 2 6% 45% 22% 1	3584
	11th to 20th	Day	40% 3 10% 28% 19%	3188
	21st to end	Day	42% 2 9% 31% 13% 2	3180
November	1st to 10th	Day	44% 3 13% 27% 13% 1	1852
	11th to 20th	Day	53% 4 13% 22% 8%	1890
	21st to end	Day	51% 3 14% 25% 7%	1754
December	1st to 10th	Day	50% 3 19% 21% 6%	2690
	11th to 20th	Day	61% 2 12% 16% 8% 1	3085
	21st to end	Day	74% 2 5% 14% 5%	4070
January	1st to 10th	Night	57% 1 9% 23% 9%	8233
	11th to 20th	Night	62% 2 8% 13% 14% 1	8280
	21st to end	Night	56% 1 11% 22% 10%	9058
February	1st to 10th	Night	54% 2 11% 20% 11% 1	2724
	11th to 20th	Night	48% 2 9% 25% 14% 1	2459
	21st to end	Night	50% 2 11% 23% 12% 2	2076
March	1st to 10th	Night	44% 2 12% 25% 13% 3	5493
	11th to 20th	Night	38% 1 13% 29% 15% 4	5438
	21st to end	Night	59% 2 9% 16% 13% 1	5072
April	1st to 10th	Night	49% 3 8% 22% 17% 1	2100
	11th to 20th	Night	49% 2 6% 22% 17% 4	2075
	21st to end	Night	44% 3 11% 25% 14% 2	1943
May	1st to 10th	Night	44% 1 9% 26% 18% 2	5264
	11th to 20th	Night	45% 1 10% 26% 17% 2	4676
	21st to end	Night	44% 1 7% 22% 19% 7%	5149
June	1st to 10th	Night	38% 4 10% 28% 19% 2	1680
	11th to 20th	Night	39% 3 10% 25% 21% 3	1680
	21st to end	Night	39% 3 15% 23% 18% 3	1680
July	1st to 10th	Night	41% 2 15% 28% 12% 3	4670
	11th to 20th	Night	27% 2 11% 34% 24% 2	4662
	21st to end	Night	33% 2 12% 27% 24% 2	5002
August	1st to 10th	Night	40% 2 13% 26% 18% 1	3717
	11th to 20th	Night	39% 2 15% 31% 12% 1	4404
	21st to end	Night	32% 2 13% 34% 16% 2	5046
September	1st to 10th	Night	33% 4 11% 29% 21% 2	2100
	11th to 20th	Night	33% 2 9% 36% 18% 2	2212
	21st to end	Night	41% 2 8% 32% 15% 1	2310
October	1st to 10th	Night	28% 1 7% 40% 23% 1	3800
	11th to 20th	Night	38% 2 12% 26% 21% 1	4017
	21st to end	Night	44% 2 9% 26% 18% 1	4610
November	1st to 10th	Night	42% 3 10% 27% 16% 2	2666
	11th to 20th	Night	50% 3 12% 22% 11% 2	2730
	21st to end	Night	51% 3 14% 23% 8% 1	2861
December	1st to 10th	Night	47% 2 16% 26% 6% 3	4720
	11th to 20th	Night	62% 2 9% 15% 10% 1	5341
	21st to end	Night	70% 2 8% 14% 6%	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	19% 9% 33% 30% 9% 1	330
	11th to 20th	Day	17% 10% 36% 25% 11% 1	330
	21st to end	Day	19% 7% 35% 31% 7% 2	363
February	1st to 10th	Day	14% 10% 38% 28% 9% 1	330
	11th to 20th	Day	15% 13% 36% 28% 8% 1	330
	21st to end	Day	19% 10% 41% 27% 4	273
March	1st to 10th	Day	15% 11% 40% 28% 6%	330
	11th to 20th	Day	17% 12% 34% 27% 9% 1	362
	21st to end	Day	24% 8% 29% 29% 8% 1	594
April	1st to 10th	Day	23% 8% 35% 26% 7%	540
	11th to 20th	Day	17% 8% 35% 27% 9% 3	532
	21st to end	Day	20% 6% 28% 31% 14% 1	540
May	1st to 10th	Day	20% 4 31% 35% 8% 2	543
	11th to 20th	Day	17% 4 26% 35% 15% 3	765
	21st to end	Day	15% 4 21% 30% 23% 7%	844
June	1st to 10th	Day	9% 4 21% 40% 22% 4	780
	11th to 20th	Day	14% 3 19% 41% 19% 4	780
	21st to end	Day	12% 3 17% 40% 25% 3	780
July	1st to 10th	Day	8% 2 10% 37% 33% 9%	771
	11th to 20th	Day	7% 2 17% 36% 30% 8%	768
	21st to end	Day	5% 2 16% 41% 31% 5%	849
August	1st to 10th	Day	10% 1 11% 38% 32% 8%	760
	11th to 20th	Day	13% 2 13% 31% 31% 11%	559
	21st to end	Day	9% 3 13% 36% 30% 10%	627
September	1st to 10th	Day	12% 4 16% 34% 25% 9%	570
	11th to 20th	Day	13% 2 14% 30% 27% 14%	570
	21st to end	Day	15% 6% 20% 27% 23% 9%	570
October	1st to 10th	Day	16% 5% 22% 29% 22% 5%	506
	11th to 20th	Day	20% 9% 26% 30% 13% 2	339
	21st to end	Day	19% 7% 31% 30% 10% 1	363
November	1st to 10th	Day	14% 11% 31% 30% 12% 2	330
	11th to 20th	Day	17% 13% 36% 24% 10%	330
	21st to end	Day	26% 8% 34% 24% 7%	330
December	1st to 10th	Day	21% 10% 37% 21% 11%	330
	11th to 20th	Day	22% 12% 38% 21% 7% 1	330
	21st to end	Day	28% 12% 34% 21% 3 2	363
January	1st to 10th	Night	20% 13% 37% 24% 6%	1050
	11th to 20th	Night	22% 12% 37% 23% 6% 1	1050
	21st to end	Night	20% 11% 37% 25% 6%	1155
February	1st to 10th	Night	21% 10% 35% 27% 7%	1039
	11th to 20th	Night	20% 9% 36% 28% 7%	823
	21st to end	Night	25% 10% 35% 26% 4	692
March	1st to 10th	Night	18% 8% 32% 30% 11% 1	840
	11th to 20th	Night	16% 9% 34% 31% 10% 1	830
	21st to end	Night	22% 6% 26% 35% 10% 2	693
April	1st to 10th	Night	21% 7% 31% 30% 10% 1	630
	11th to 20th	Night	25% 4 27% 27% 13% 3	623
	21st to end	Night	21% 4 21% 36% 16% 2	630
May	1st to 10th	Night	16% 4 20% 41% 16% 2	630
	11th to 20th	Night	19% 2 22% 33% 21% 3	621
	21st to end	Night	14% 2 16% 35% 26% 7%	683
June	1st to 10th	Night	13% 2 14% 39% 28% 5%	630
	11th to 20th	Night	16% 2 16% 37% 25% 5%	630
	21st to end	Night	11% 2 14% 38% 31% 3	630
July	1st to 10th	Night	10% 1 6% 33% 40% 10%	615
	11th to 20th	Night	8% 1 11% 35% 34% 9%	612
	21st to end	Night	8% 1 12% 39% 35% 5%	690
August	1st to 10th	Night	8% 2 10% 37% 36% 8%	627
	11th to 20th	Night	11% 2 11% 33% 33% 10%	624
	21st to end	Night	11% 2 12% 35% 35% 5%	693
September	1st to 10th	Night	10% 2 15% 34% 29% 10%	630
	11th to 20th	Night	13% 4 14% 27% 31% 12%	742
	21st to end	Night	17% 6% 18% 25% 25% 9%	840
October	1st to 10th	Night	18% 4 23% 28% 23% 4	840
	11th to 20th	Night	21% 7% 31% 28% 12% 1	813
	21st to end	Night	26% 7% 28% 26% 11% 1	880
November	1st to 10th	Night	18% 8% 34% 28% 10% 2	820
	11th to 20th	Night	20% 14% 35% 23% 8%	840
	21st to end	Night	23% 11% 34% 25% 7%	971
December	1st to 10th	Night	24% 13% 36% 22% 5%	1050
	11th to 20th	Night	24% 12% 36% 21% 7%	1050
	21st to end	Night	30% 12% 33% 21% 4	1155

Page generated at 2026-10-11 04:06:28. Version ac07

Copyright © 2026 Attilla Danko.