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 2025-06-10.

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	12% 8% 3 7% 5% 5% 5% 4 6% 7% 38%	119502
	Night	14% 10% 3 8% 5% 4 4 4 5% 7% 37%	118926
Transparency	Day	45% 3 12% 26% 13% 2	123034
	Night	47% 2 11% 24% 14% 2	123522
Seeing	Day	15% 6% 26% 31% 18% 4	16664
	Night	19% 7% 27% 29% 16% 3	26607

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	10% 11% 5% 13% 6% 5% 6% 5% 6% 7% 27%	3617
	11th to 20th	Day	9% 10% 5% 11% 5% 4 6% 6% 9% 7% 29%	3620
	21st to end	Day	12% 15% 7% 8% 4 4 3 3 5% 7% 31%	3982
February	1st to 10th	Day	11% 13% 6% 9% 6% 5% 6% 4 5% 7% 28%	1799
	11th to 20th	Day	13% 11% 4 8% 5% 5% 5% 5% 6% 6% 35%	1948
	21st to end	Day	12% 12% 5% 10% 5% 4 5% 4 6% 5% 32%	1650
March	1st to 10th	Day	13% 8% 3 7% 5% 3 4 4 5% 6% 44%	4480
	11th to 20th	Day	11% 6% 2 7% 6% 5% 5% 4 5% 6% 43%	4666
	21st to end	Day	19% 11% 4 10% 5% 5% 4 3 5% 5% 28%	5967
April	1st to 10th	Day	17% 12% 3 7% 5% 4 5% 4 5% 7% 32%	2400
	11th to 20th	Day	15% 9% 3 7% 5% 6% 4 4 6% 6% 35%	2374
	21st to end	Day	16% 9% 3 7% 5% 5% 5% 4 6% 6% 34%	2550
May	1st to 10th	Day	15% 7% 3 7% 4 4 4 4 6% 6% 39%	5862
	11th to 20th	Day	12% 8% 2 7% 5% 6% 6% 4 6% 7% 36%	6309
	21st to end	Day	15% 6% 2 5% 4 4 4 4 6% 9% 41%	6935
June	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 5% 6% 9% 44%	2787
	11th to 20th	Day	10% 6% 2 6% 5% 4 5% 4 6% 8% 43%	2660
	21st to end	Day	9% 5% 2 6% 4 5% 5% 5% 8% 8% 44%	2660
July	1st to 10th	Day	12% 7% 3 7% 5% 5% 5% 4 6% 9% 37%	4440
	11th to 20th	Day	4 3 2 4 4 4 5% 5% 8% 12% 49%	4440
	21st to end	Day	6% 5% 2 6% 5% 5% 5% 4 6% 9% 48%	4813
August	1st to 10th	Day	10% 5% 2 5% 5% 4 6% 5% 7% 8% 44%	4396
	11th to 20th	Day	10% 4 2 5% 4 4 5% 4 6% 8% 48%	3835
	21st to end	Day	8% 6% 2 6% 5% 4 5% 4 6% 9% 45%	4180
September	1st to 10th	Day	11% 5% 2 6% 4 4 4 3 7% 7% 47%	2280
	11th to 20th	Day	11% 5% 2 5% 4 4 4 4 4 8% 50%	2159
	21st to end	Day	12% 6% 2 6% 5% 5% 5% 3 6% 9% 42%	2090
October	1st to 10th	Day	14% 6% 2 6% 3 3 4 4 5% 7% 45%	2032
	11th to 20th	Day	18% 8% 3 7% 5% 4 5% 4 6% 7% 32%	1857
	21st to end	Day	16% 8% 3 8% 6% 5% 4 4 4 6% 37%	1881
November	1st to 10th	Day	12% 8% 3 8% 5% 4 4 3 5% 7% 42%	1762
	11th to 20th	Day	11% 12% 4 9% 7% 6% 5% 4 6% 7% 29%	1800
	21st to end	Day	18% 12% 3 7% 5% 4 3 3 4 6% 37%	1671
December	1st to 10th	Day	10% 10% 4 8% 6% 6% 5% 4 6% 7% 35%	2610
	11th to 20th	Day	13% 14% 4 9% 6% 7% 6% 5% 7% 6% 23%	3008
	21st to end	Day	22% 19% 7% 11% 5% 4 4 4 3 5% 16%	3982
January	1st to 10th	Night	11% 12% 6% 12% 5% 5% 4 3 5% 5% 32%	6348
	11th to 20th	Night	11% 13% 6% 13% 7% 5% 6% 5% 7% 5% 22%	6360
	21st to end	Night	13% 15% 5% 9% 5% 4 4 3 5% 7% 31%	6996
February	1st to 10th	Night	13% 14% 5% 8% 5% 5% 4 4 6% 5% 32%	2595
	11th to 20th	Night	12% 11% 3 7% 5% 4 5% 4 4 5% 38%	2338
	21st to end	Night	18% 12% 3 7% 3 3 4 3 5% 6% 35%	1980
March	1st to 10th	Night	16% 7% 3 6% 3 4 4 4 4 6% 43%	5373
	11th to 20th	Night	10% 6% 2 6% 4 4 5% 4 6% 9% 45%	5320
	21st to end	Night	18% 11% 5% 10% 6% 5% 4 3 4 5% 30%	4962
April	1st to 10th	Night	17% 9% 3 6% 5% 4 4 4 5% 6% 38%	2000
	11th to 20th	Night	20% 9% 2 6% 4 3 4 3 4 6% 38%	1975
	21st to end	Night	18% 8% 2 5% 4 4 3 4 5% 7% 40%	1850
May	1st to 10th	Night	15% 8% 3 7% 4 5% 4 4 6% 7% 38%	4033
	11th to 20th	Night	12% 8% 5% 7% 4 4 5% 4 5% 6% 38%	3601
	21st to end	Night	17% 7% 3 6% 5% 4 4 3 5% 6% 42%	3942
June	1st to 10th	Night	11% 4 2 5% 5% 4 6% 5% 5% 7% 46%	1597
	11th to 20th	Night	12% 6% 3 5% 4 3 4 4 6% 9% 43%	1520
	21st to end	Night	9% 7% 3 6% 5% 4 4 3 5% 8% 46%	1520
July	1st to 10th	Night	13% 7% 2 6% 5% 5% 4 4 7% 7% 41%	2530
	11th to 20th	Night	4 3 1 4 5% 4 4 4 7% 8% 56%	2530
	21st to end	Night	6% 4 2 6% 4 5% 5% 4 7% 9% 49%	2750
August	1st to 10th	Night	10% 5% 2 5% 4 3 4 4 6% 10% 48%	2542
	11th to 20th	Night	9% 5% 2 6% 4 4 4 4 6% 8% 49%	2977
	21st to end	Night	8% 4 2 5% 4 4 4 4 6% 9% 49%	3476
September	1st to 10th	Night	9% 4 2 6% 4 4 4 3 5% 7% 52%	1900
	11th to 20th	Night	11% 4 1 5% 4 3 4 3 5% 7% 53%	2001
	21st to end	Night	13% 7% 3 7% 4 4 3 3 5% 7% 46%	2090
October	1st to 10th	Night	14% 6% 2 6% 3 4 4 2 5% 6% 47%	2145
	11th to 20th	Night	18% 7% 2 6% 4 3 3 3 5% 6% 42%	2322
	21st to end	Night	19% 9% 3 7% 4 4 4 3 5% 7% 34%	2717
November	1st to 10th	Night	12% 8% 3 6% 5% 3 4 3 4 7% 45%	2536
	11th to 20th	Night	14% 11% 3 8% 5% 4 6% 4 5% 6% 34%	2600
	21st to end	Night	17% 10% 4 6% 5% 5% 5% 3 5% 6% 34%	2725
December	1st to 10th	Night	11% 11% 3 7% 4 4 5% 3 5% 7% 40%	4580
	11th to 20th	Night	16% 17% 5% 9% 5% 5% 4 3 5% 5% 26%	5199
	21st to end	Night	21% 18% 5% 11% 5% 5% 4 3 4 5% 18%	6996

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	57% 2 14% 21% 7%	3618
	11th to 20th	Day	53% 2 11% 18% 15% 1	3620
	21st to end	Day	55% 1 9% 22% 13%	3982
February	1st to 10th	Day	55% 4 11% 20% 9% 1	1799
	11th to 20th	Day	50% 2 11% 24% 10% 2	1958
	21st to end	Day	53% 3 11% 20% 11% 2	1650
March	1st to 10th	Day	43% 2 12% 26% 12% 6%	4480
	11th to 20th	Day	43% 1 13% 26% 14% 2	4666
	21st to end	Day	59% 2 11% 16% 10% 1	5969
April	1st to 10th	Day	52% 4 11% 21% 11% 1	2400
	11th to 20th	Day	48% 4 10% 22% 13% 3	2374
	21st to end	Day	49% 4 13% 20% 12% 2	2550
May	1st to 10th	Day	46% 2 9% 26% 15% 2	5897
	11th to 20th	Day	48% 2 9% 27% 14% 1	6313
	21st to end	Day	41% 2 10% 29% 15% 3	6949
June	1st to 10th	Day	38% 3 12% 27% 17% 3	2787
	11th to 20th	Day	38% 3 14% 25% 19% 1	2660
	21st to end	Day	36% 5% 16% 26% 17% 2	2660
July	1st to 10th	Day	44% 3 12% 28% 12% 2	4371
	11th to 20th	Day	28% 3 17% 35% 16% 1	4365
	21st to end	Day	33% 4 16% 24% 19% 4	4662
August	1st to 10th	Day	37% 3 16% 31% 12% 1	4381
	11th to 20th	Day	33% 3 14% 37% 12% 1	3874
	21st to end	Day	37% 3 14% 26% 19% 2	4179
September	1st to 10th	Day	36% 5% 11% 31% 15% 2	2280
	11th to 20th	Day	33% 3 11% 35% 16% 1	2159
	21st to end	Day	40% 3 11% 32% 13% 1	2090
October	1st to 10th	Day	25% 2 6% 44% 22% 1	3370
	11th to 20th	Day	40% 3 10% 28% 19%	3060
	21st to end	Day	43% 2 9% 31% 13% 2	3081
November	1st to 10th	Day	44% 3 13% 27% 12% 1	1762
	11th to 20th	Day	54% 4 13% 21% 8%	1800
	21st to end	Day	51% 3 14% 25% 7%	1671
December	1st to 10th	Day	50% 3 20% 21% 6%	2610
	11th to 20th	Day	61% 2 12% 16% 8% 1	3005
	21st to end	Day	74% 2 5% 14% 5%	3982
January	1st to 10th	Night	57% 1 8% 23% 11%	6348
	11th to 20th	Night	62% 2 8% 12% 14% 1	6360
	21st to end	Night	56% 1 13% 19% 10%	6996
February	1st to 10th	Night	54% 3 11% 20% 11% 1	2595
	11th to 20th	Night	49% 3 9% 24% 14% 1	2339
	21st to end	Night	51% 2 11% 21% 12% 2	1980
March	1st to 10th	Night	44% 2 12% 26% 13% 3	5373
	11th to 20th	Night	37% 1 13% 29% 15% 3	5320
	21st to end	Night	59% 2 9% 16% 13% 1	4962
April	1st to 10th	Night	48% 3 8% 23% 17% 1	2000
	11th to 20th	Night	49% 3 6% 21% 17% 4	1975
	21st to end	Night	44% 3 11% 25% 15% 2	1850
May	1st to 10th	Night	47% 2 11% 20% 18% 2	4060
	11th to 20th	Night	48% 1 10% 22% 16% 2	3602
	21st to end	Night	46% 2 8% 24% 14% 6%	3950
June	1st to 10th	Night	37% 4 11% 29% 17% 2	1597
	11th to 20th	Night	38% 3 9% 26% 22% 3	1520
	21st to end	Night	37% 4 14% 24% 18% 2	1520
July	1st to 10th	Night	43% 3 14% 24% 12% 5%	2490
	11th to 20th	Night	27% 3 14% 37% 17% 3	2482
	21st to end	Night	32% 3 15% 22% 25% 3	2662
August	1st to 10th	Night	33% 3 15% 28% 19% 2	2533
	11th to 20th	Night	34% 2 11% 34% 17% 1	3004
	21st to end	Night	32% 3 12% 28% 21% 3	3476
September	1st to 10th	Night	32% 4 10% 28% 23% 2	1900
	11th to 20th	Night	32% 2 9% 37% 18% 2	2001
	21st to end	Night	41% 2 8% 32% 15% 1	2090
October	1st to 10th	Night	28% 2 7% 40% 23% 1	3574
	11th to 20th	Night	37% 2 12% 26% 21% 1	3858
	21st to end	Night	45% 2 9% 26% 18% 1	4467
November	1st to 10th	Night	41% 3 10% 27% 16% 2	2536
	11th to 20th	Night	51% 3 12% 21% 11% 1	2600
	21st to end	Night	51% 3 15% 23% 8% 1	2725
December	1st to 10th	Night	46% 2 17% 27% 6% 3	4580
	11th to 20th	Night	62% 2 10% 15% 10% 1	5201
	21st to end	Night	71% 2 8% 14% 6%	6996

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	18% 10% 34% 29% 9% 1	300
	11th to 20th	Day	18% 10% 35% 25% 11% 1	300
	21st to end	Day	21% 6% 33% 31% 7% 2	330
February	1st to 10th	Day	15% 11% 39% 26% 8% 1	300
	11th to 20th	Day	16% 14% 36% 25% 8% 1	300
	21st to end	Day	19% 10% 42% 24% 4	249
March	1st to 10th	Day	14% 11% 42% 26% 6%	300
	11th to 20th	Day	16% 12% 36% 25% 10% 2	330
	21st to end	Day	26% 8% 29% 27% 8% 1	550
April	1st to 10th	Day	23% 8% 35% 26% 8%	500
	11th to 20th	Day	17% 9% 36% 26% 9% 3	492
	21st to end	Day	21% 7% 29% 29% 13% 1	500
May	1st to 10th	Day	20% 5% 32% 33% 8% 2	503
	11th to 20th	Day	18% 4 25% 34% 15% 3	715
	21st to end	Day	15% 4 22% 30% 22% 7%	789
June	1st to 10th	Day	10% 4 22% 40% 21% 4	726
	11th to 20th	Day	13% 3 20% 40% 19% 4	680
	21st to end	Day	11% 3 19% 40% 24% 4	680
July	1st to 10th	Day	8% 2 12% 37% 32% 10%	671
	11th to 20th	Day	7% 2 18% 37% 28% 8%	668
	21st to end	Day	5% 2 17% 41% 29% 6%	739
August	1st to 10th	Day	10% 2 12% 37% 32% 8%	662
	11th to 20th	Day	10% 2 15% 31% 30% 11%	479
	21st to end	Day	9% 3 14% 36% 29% 9%	539
September	1st to 10th	Day	12% 3 17% 34% 25% 9%	490
	11th to 20th	Day	11% 3 15% 31% 29% 12%	490
	21st to end	Day	15% 7% 23% 27% 21% 7%	490
October	1st to 10th	Day	18% 6% 25% 26% 21% 4	432
	11th to 20th	Day	21% 10% 28% 27% 13% 2	300
	21st to end	Day	20% 8% 34% 28% 8% 2	330
November	1st to 10th	Day	14% 11% 30% 30% 12% 2	300
	11th to 20th	Day	17% 14% 36% 23% 10%	300
	21st to end	Day	26% 8% 36% 23% 8%	300
December	1st to 10th	Day	21% 10% 38% 21% 10%	300
	11th to 20th	Day	23% 12% 36% 21% 7% 1	300
	21st to end	Day	28% 12% 35% 20% 4 2	330
January	1st to 10th	Night	20% 13% 37% 23% 7%	1000
	11th to 20th	Night	22% 12% 37% 23% 6% 1	1000
	21st to end	Night	21% 10% 36% 26% 6%	1100
February	1st to 10th	Night	21% 10% 36% 26% 7% 1	990
	11th to 20th	Night	20% 10% 37% 27% 6%	783
	21st to end	Night	26% 10% 34% 26% 4	660
March	1st to 10th	Night	18% 9% 32% 30% 11% 1	800
	11th to 20th	Night	14% 9% 34% 31% 10% 1	790
	21st to end	Night	23% 6% 25% 35% 10% 2	660
April	1st to 10th	Night	21% 7% 31% 30% 11% 1	600
	11th to 20th	Night	25% 5% 27% 27% 13% 3	593
	21st to end	Night	22% 4 21% 36% 16% 2	600
May	1st to 10th	Night	17% 4 21% 40% 16% 2	600
	11th to 20th	Night	20% 3 21% 32% 21% 3	591
	21st to end	Night	14% 2 16% 34% 26% 7%	650
June	1st to 10th	Night	13% 2 15% 39% 27% 5%	599
	11th to 20th	Night	15% 2 16% 36% 25% 5%	570
	21st to end	Night	10% 2 16% 38% 31% 3	570
July	1st to 10th	Night	10% 1 6% 33% 39% 10%	555
	11th to 20th	Night	8% 2 13% 36% 33% 9%	552
	21st to end	Night	8% 1 13% 39% 34% 5%	624
August	1st to 10th	Night	7% 2 10% 37% 36% 8%	567
	11th to 20th	Night	10% 2 12% 32% 32% 11%	564
	21st to end	Night	11% 2 13% 34% 35% 5%	627
September	1st to 10th	Night	11% 2 15% 34% 29% 9%	570
	11th to 20th	Night	12% 4 15% 28% 31% 11%	671
	21st to end	Night	18% 6% 19% 24% 24% 8%	760
October	1st to 10th	Night	18% 5% 24% 26% 24% 4	760
	11th to 20th	Night	22% 8% 31% 26% 12% 1	760
	21st to end	Night	27% 8% 28% 26% 10% 1	836
November	1st to 10th	Night	18% 9% 33% 28% 11% 2	780
	11th to 20th	Night	21% 14% 35% 22% 8%	800
	21st to end	Night	22% 11% 35% 24% 7%	925
December	1st to 10th	Night	24% 13% 36% 22% 5%	1000
	11th to 20th	Night	25% 11% 35% 21% 7%	1000
	21st to end	Night	30% 12% 33% 22% 4	1100

Page generated at 2025-06-07 09:28:19. Version ac07

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