Maumee
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Maumee clear sky chart from 2005-11-06 to 2026-06-16.

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% 9% 3 7% 5% 4 4 4 5% 7% 37%	136955
	Night	15% 9% 3 7% 5% 4 4 3 5% 7% 37%	135222
Transparency	Day	44% 5% 10% 23% 15% 2	140567
	Night	45% 5% 10% 23% 15% 2	139685
Seeing	Day	21% 14% 28% 22% 12% 4	17650
	Night	20% 13% 27% 25% 13% 2	27480

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	15% 14% 6% 9% 4 4 4 4 5% 7% 30%	4691
	11th to 20th	Day	11% 12% 5% 13% 6% 4 3 3 5% 4 33%	4710
	21st to end	Day	17% 13% 5% 10% 7% 5% 5% 3 4 4 27%	5595
February	1st to 10th	Day	18% 12% 6% 8% 4 4 3 3 5% 7% 31%	2100
	11th to 20th	Day	16% 10% 4 10% 5% 4 4 4 5% 5% 34%	2048
	21st to end	Day	16% 14% 4 9% 4 3 3 3 4 6% 34%	1730
March	1st to 10th	Day	20% 13% 5% 7% 3 3 3 2 3 4 38%	4580
	11th to 20th	Day	13% 9% 3 6% 4 3 4 3 5% 8% 42%	4902
	21st to end	Day	16% 10% 3 8% 4 4 5% 4 6% 7% 33%	5849
April	1st to 10th	Day	15% 9% 3 7% 5% 4 4 3 5% 8% 36%	2520
	11th to 20th	Day	17% 9% 3 6% 4 4 3 3 5% 6% 39%	2494
	21st to end	Day	19% 8% 2 7% 4 4 4 3 4 7% 38%	2673
May	1st to 10th	Day	18% 8% 3 8% 5% 5% 5% 4 7% 9% 30%	7616
	11th to 20th	Day	18% 7% 3 6% 4 4 4 4 5% 6% 39%	7626
	21st to end	Day	16% 8% 3 9% 6% 5% 6% 5% 6% 9% 27%	8427
June	1st to 10th	Day	12% 6% 2 5% 5% 4 4 4 6% 8% 44%	2940
	11th to 20th	Day	9% 5% 2 7% 5% 5% 5% 5% 6% 9% 43%	2871
	21st to end	Day	9% 6% 2 6% 5% 5% 5% 5% 6% 9% 42%	2800
July	1st to 10th	Day	11% 6% 2 6% 4 4 5% 4 6% 11% 41%	6360
	11th to 20th	Day	8% 5% 2 7% 5% 6% 6% 5% 7% 10% 38%	6360
	21st to end	Day	10% 7% 3 8% 6% 6% 6% 6% 7% 9% 32%	6636
August	1st to 10th	Day	9% 4 2 5% 4 3 5% 4 7% 11% 47%	4234
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 5% 8% 10% 40%	3924
	21st to end	Day	5% 4 2 5% 4 4 4 4 6% 9% 54%	4312
September	1st to 10th	Day	12% 5% 2 6% 3 4 4 4 5% 7% 48%	2366
	11th to 20th	Day	10% 5% 2 5% 4 4 4 4 6% 9% 49%	2200
	21st to end	Day	13% 5% 2 5% 4 3 4 3 5% 6% 50%	2200
October	1st to 10th	Day	11% 5% 2 5% 4 3 4 3 5% 6% 53%	2200
	11th to 20th	Day	12% 6% 2 5% 4 4 4 4 6% 6% 47%	2069
	21st to end	Day	19% 8% 3 6% 4 4 3 3 5% 6% 38%	1980
November	1st to 10th	Day	9% 7% 2 5% 3 3 4 3 5% 7% 51%	1852
	11th to 20th	Day	16% 11% 3 6% 4 3 4 3 5% 7% 40%	1890
	21st to end	Day	19% 11% 4 6% 3 4 3 3 4 5% 38%	1890
December	1st to 10th	Day	15% 12% 3 6% 3 3 3 3 4 5% 43%	3020
	11th to 20th	Day	16% 13% 5% 9% 5% 5% 5% 4 4 5% 29%	3220
	21st to end	Day	25% 18% 6% 8% 4 4 4 3 4 5% 19%	4070
January	1st to 10th	Night	15% 14% 6% 10% 5% 5% 4 4 5% 5% 27%	8232
	11th to 20th	Night	12% 15% 6% 14% 7% 5% 5% 3 3 5% 26%	8280
	21st to end	Night	17% 11% 5% 8% 6% 4 4 3 4 5% 33%	8580
February	1st to 10th	Night	19% 12% 5% 9% 5% 4 4 3 5% 5% 28%	2520
	11th to 20th	Night	17% 12% 4 9% 5% 4 3 3 5% 6% 32%	2458
	21st to end	Night	19% 12% 4 9% 4 4 4 3 5% 5% 33%	2076
March	1st to 10th	Night	21% 14% 3 6% 3 3 3 3 4 5% 36%	5493
	11th to 20th	Night	13% 7% 3 6% 4 4 4 3 5% 7% 46%	5278
	21st to end	Night	16% 9% 3 8% 6% 5% 5% 4 5% 6% 33%	5365
April	1st to 10th	Night	15% 9% 2 6% 5% 4 4 4 7% 6% 40%	2100
	11th to 20th	Night	15% 8% 2 6% 4 3 4 4 5% 6% 41%	2075
	21st to end	Night	16% 7% 3 6% 4 3 5% 4 6% 8% 37%	1944
May	1st to 10th	Night	19% 9% 3 7% 4 4 5% 3 6% 8% 32%	5237
	11th to 20th	Night	16% 7% 3 6% 4 4 5% 4 6% 8% 38%	5234
	21st to end	Night	15% 8% 3 8% 5% 5% 6% 4 6% 8% 31%	5710
June	1st to 10th	Night	11% 5% 2 5% 4 4 4 4 6% 8% 47%	1680
	11th to 20th	Night	9% 5% 2 6% 4 4 4 4 6% 10% 47%	1640
	21st to end	Night	6% 4 1 4 3 4 4 5% 8% 10% 51%	1600
July	1st to 10th	Night	9% 5% 2 6% 4 5% 4 4 6% 9% 46%	3618
	11th to 20th	Night	7% 5% 2 6% 4 4 4 5% 7% 10% 44%	3617
	21st to end	Night	8% 5% 2 7% 5% 5% 6% 6% 7% 11% 38%	4209
August	1st to 10th	Night	9% 5% 2 5% 4 4 4 3 5% 9% 51%	2915
	11th to 20th	Night	7% 5% 2 6% 5% 5% 5% 4 6% 9% 47%	3121
	21st to end	Night	4 2 1 4 3 3 5% 4 6% 9% 59%	3586
September	1st to 10th	Night	11% 4 2 5% 4 4 4 3 4 7% 52%	2013
	11th to 20th	Night	7% 4 2 5% 3 3 4 3 5% 8% 56%	2200
	21st to end	Night	14% 6% 2 4 4 3 4 3 4 6% 50%	2200
October	1st to 10th	Night	9% 4 1 4 3 3 3 3 5% 6% 59%	2200
	11th to 20th	Night	15% 6% 2 6% 3 3 4 3 4 6% 49%	2327
	21st to end	Night	18% 8% 2 6% 4 3 4 3 5% 5% 42%	2860
November	1st to 10th	Night	12% 7% 2 5% 4 3 3 3 4 7% 49%	2666
	11th to 20th	Night	15% 9% 3 6% 4 3 4 3 4 6% 42%	2730
	21st to end	Night	19% 11% 4 7% 5% 3 4 3 4 6% 35%	2730
December	1st to 10th	Night	18% 11% 3 8% 4 3 3 3 3 4 39%	4380
	11th to 20th	Night	19% 13% 5% 10% 5% 4 4 3 5% 5% 29%	5198
	21st to end	Night	27% 18% 6% 9% 5% 4 4 2 3 4 19%	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	55% 3 11% 22% 8% 1	4692
	11th to 20th	Day	53% 3 8% 18% 15% 3	4710
	21st to end	Day	62% 2 8% 17% 5% 5%	5595
February	1st to 10th	Day	54% 3 8% 23% 10% 2	2100
	11th to 20th	Day	51% 4 9% 23% 12% 1	2058
	21st to end	Day	52% 4 9% 23% 10% 3	1730
March	1st to 10th	Day	53% 2 5% 18% 16% 6%	4580
	11th to 20th	Day	42% 4 8% 30% 14% 2	4902
	21st to end	Day	49% 5% 12% 21% 12% 1	5851
April	1st to 10th	Day	46% 5% 12% 22% 15% 1	2520
	11th to 20th	Day	45% 4 9% 24% 13% 3	2494
	21st to end	Day	47% 4 9% 24% 13% 3	2673
May	1st to 10th	Day	50% 6% 12% 21% 11%	7651
	11th to 20th	Day	46% 5% 10% 23% 16%	7630
	21st to end	Day	51% 7% 11% 17% 12% 2	8441
June	1st to 10th	Day	38% 6% 11% 25% 17% 3	2940
	11th to 20th	Day	37% 6% 13% 23% 19% 3	2871
	21st to end	Day	36% 8% 14% 20% 18% 4	2800
July	1st to 10th	Day	37% 6% 11% 25% 20% 1	6291
	11th to 20th	Day	38% 9% 13% 25% 15% 1	6285
	21st to end	Day	45% 8% 13% 21% 11% 1	6447
August	1st to 10th	Day	30% 6% 14% 34% 14% 1	4221
	11th to 20th	Day	35% 6% 12% 30% 16% 1	3962
	21st to end	Day	26% 5% 14% 34% 18% 4	4311
September	1st to 10th	Day	35% 6% 10% 26% 19% 5%	2366
	11th to 20th	Day	32% 4 11% 29% 20% 4	2200
	21st to end	Day	35% 4 9% 24% 25% 2	2200
October	1st to 10th	Day	22% 3 6% 31% 36% 1	3590
	11th to 20th	Day	28% 4 9% 28% 29% 2	3337
	21st to end	Day	38% 3 8% 24% 25% 2	3180
November	1st to 10th	Day	33% 4 10% 32% 18% 4	1852
	11th to 20th	Day	44% 5% 8% 23% 16% 4	1890
	21st to end	Day	50% 4 9% 22% 15% 1	1890
December	1st to 10th	Day	45% 3 10% 27% 15%	3020
	11th to 20th	Day	57% 4 8% 21% 9% 1	3217
	21st to end	Day	67% 4 10% 12% 6%	4070
January	1st to 10th	Night	58% 4 10% 20% 8%	8233
	11th to 20th	Night	60% 4 8% 13% 12% 3	8280
	21st to end	Night	54% 3 10% 22% 11% 1	8580
February	1st to 10th	Night	57% 5% 11% 19% 7% 1	2520
	11th to 20th	Night	53% 3 10% 21% 12% 1	2459
	21st to end	Night	53% 4 10% 19% 12% 2	2076
March	1st to 10th	Night	52% 3 5% 24% 12% 4	5493
	11th to 20th	Night	38% 4 10% 25% 21% 1	5278
	21st to end	Night	51% 4 8% 26% 9% 1	5365
April	1st to 10th	Night	43% 5% 10% 25% 13% 2	2100
	11th to 20th	Night	42% 5% 11% 19% 18% 5%	2075
	21st to end	Night	44% 6% 10% 25% 13% 3	1944
May	1st to 10th	Night	50% 5% 11% 24% 8% 2	5264
	11th to 20th	Night	44% 5% 12% 23% 15%	5235
	21st to end	Night	49% 7% 14% 19% 10% 2	5720
June	1st to 10th	Night	34% 6% 11% 24% 22% 4	1680
	11th to 20th	Night	33% 5% 12% 24% 20% 5%	1640
	21st to end	Night	24% 8% 17% 26% 21% 5%	1600
July	1st to 10th	Night	34% 6% 10% 26% 20% 3	3580
	11th to 20th	Night	33% 8% 15% 28% 14% 2	3572
	21st to end	Night	37% 8% 15% 26% 11% 2	4085
August	1st to 10th	Night	31% 6% 13% 36% 12% 1	2904
	11th to 20th	Night	30% 7% 14% 30% 18% 1	3149
	21st to end	Night	22% 6% 14% 32% 23% 3	3586
September	1st to 10th	Night	32% 5% 10% 27% 20% 7%	2013
	11th to 20th	Night	26% 5% 9% 27% 28% 4	2200
	21st to end	Night	35% 4 10% 23% 25% 4	2200
October	1st to 10th	Night	19% 3 7% 21% 47% 4	3590
	11th to 20th	Night	26% 2 7% 25% 36% 3	3798
	21st to end	Night	34% 3 7% 23% 27% 5%	4610
November	1st to 10th	Night	36% 4 9% 25% 22% 4	2666
	11th to 20th	Night	42% 4 9% 22% 19% 4	2730
	21st to end	Night	52% 3 9% 22% 13% 1	2730
December	1st to 10th	Night	50% 3 10% 24% 13%	4380
	11th to 20th	Night	56% 4 10% 18% 10% 1	5200
	21st to end	Night	70% 4 8% 13% 5%	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	33% 20% 29% 16% 1 1	330
	11th to 20th	Day	38% 26% 28% 7% 1	330
	21st to end	Day	33% 28% 29% 9% 2	363
February	1st to 10th	Day	31% 28% 28% 11% 2	330
	11th to 20th	Day	32% 29% 29% 8% 1	330
	21st to end	Day	29% 26% 36% 8%	273
March	1st to 10th	Day	33% 26% 32% 9% 1	330
	11th to 20th	Day	34% 22% 29% 11% 3 1	456
	21st to end	Day	32% 22% 30% 12% 3 1	594
April	1st to 10th	Day	29% 18% 31% 16% 5% 1	540
	11th to 20th	Day	27% 22% 25% 18% 6% 2	532
	21st to end	Day	27% 19% 34% 11% 6% 1	540
May	1st to 10th	Day	26% 18% 31% 16% 6% 2	543
	11th to 20th	Day	24% 16% 29% 19% 8% 4	567
	21st to end	Day	15% 13% 30% 22% 14% 6%	627
June	1st to 10th	Day	14% 9% 32% 26% 15% 4	780
	11th to 20th	Day	10% 9% 29% 32% 15% 4	756
	21st to end	Day	12% 9% 30% 27% 16% 6%	730
July	1st to 10th	Day	13% 5% 19% 28% 22% 12%	721
	11th to 20th	Day	7% 6% 27% 33% 20% 7%	718
	21st to end	Day	10% 5% 22% 35% 21% 8%	671
August	1st to 10th	Day	10% 4 20% 33% 24% 10%	526
	11th to 20th	Day	15% 5% 25% 28% 21% 6%	519
	21st to end	Day	8% 5% 18% 33% 26% 9%	583
September	1st to 10th	Day	12% 7% 21% 31% 22% 8%	530
	11th to 20th	Day	12% 1 17% 32% 26% 12%	530
	21st to end	Day	19% 10% 20% 25% 20% 6%	530
October	1st to 10th	Day	11% 7% 29% 30% 18% 5%	530
	11th to 20th	Day	16% 18% 32% 23% 9% 2	465
	21st to end	Day	32% 15% 36% 16% 1	363
November	1st to 10th	Day	18% 19% 33% 23% 5% 2	330
	11th to 20th	Day	27% 22% 29% 16% 5% 1	330
	21st to end	Day	32% 15% 35% 14% 3 1	330
December	1st to 10th	Day	27% 28% 30% 11% 4 1	330
	11th to 20th	Day	32% 18% 35% 11% 3 1	330
	21st to end	Day	36% 20% 31% 10% 2	363
January	1st to 10th	Night	28% 20% 31% 18% 3	1050
	11th to 20th	Night	30% 23% 32% 14% 2	1050
	21st to end	Night	25% 21% 34% 18% 2	1029
February	1st to 10th	Night	28% 17% 36% 17% 2	840
	11th to 20th	Night	27% 24% 30% 17% 2	823
	21st to end	Night	29% 18% 37% 15% 1	692
March	1st to 10th	Night	27% 19% 30% 21% 2	840
	11th to 20th	Night	26% 19% 32% 18% 5%	840
	21st to end	Night	26% 17% 29% 23% 4	830
April	1st to 10th	Night	21% 16% 35% 23% 6% 1	630
	11th to 20th	Night	22% 16% 30% 23% 8% 1	623
	21st to end	Night	20% 13% 35% 24% 7% 1	630
May	1st to 10th	Night	22% 11% 32% 26% 9%	630
	11th to 20th	Night	15% 10% 29% 27% 16% 3	621
	21st to end	Night	13% 6% 26% 30% 21% 4	683
June	1st to 10th	Night	12% 6% 25% 34% 21% 1	630
	11th to 20th	Night	10% 5% 22% 40% 21% 1	615
	21st to end	Night	7% 3 25% 37% 26% 3	600
July	1st to 10th	Night	11% 2 13% 34% 31% 9%	585
	11th to 20th	Night	9% 3 16% 35% 32% 5%	582
	21st to end	Night	9% 2 15% 40% 31% 4	657
August	1st to 10th	Night	8% 2 15% 37% 33% 5%	597
	11th to 20th	Night	7% 2 15% 36% 35% 5%	594
	21st to end	Night	5% 2 17% 34% 35% 6%	660
September	1st to 10th	Night	12% 5% 13% 34% 32% 4	613
	11th to 20th	Night	8% 3 18% 32% 34% 5%	800
	21st to end	Night	17% 7% 21% 29% 23% 3	800
October	1st to 10th	Night	11% 7% 25% 31% 23% 5%	800
	11th to 20th	Night	18% 11% 28% 26% 14% 2	800
	21st to end	Night	23% 14% 32% 22% 8% 1	880
November	1st to 10th	Night	17% 13% 31% 26% 12% 1	820
	11th to 20th	Night	23% 18% 28% 23% 7%	840
	21st to end	Night	28% 17% 24% 25% 6%	840
December	1st to 10th	Night	27% 17% 33% 19% 5%	840
	11th to 20th	Night	27% 16% 30% 21% 4 1	961
	21st to end	Night	35% 17% 29% 15% 3	1155

Page generated at 2026-06-13 02:31:42. Version ac07

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