Matthies Memorial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Matthies Memorial 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	17% 7% 2 6% 4 4 4 4 6% 7% 39%	149068
	Night	18% 8% 3 6% 4 4 4 3 5% 6% 41%	142316
Transparency	Day	42% 7% 13% 22% 15% 2	152586
	Night	42% 5% 12% 22% 16% 3	146887
Seeing	Day	21% 17% 32% 21% 8% 2	17459
	Night	21% 14% 32% 25% 8% 1	26438

By Month

Percentage Cloud Cover NE (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% 8% 2 8% 5% 5% 4 4 5% 5% 42%	4661
	11th to 20th	Day	16% 7% 3 7% 4 4 4 3 4 5% 43%	4650
	21st to end	Day	15% 8% 2 7% 4 3 3 4 5% 7% 43%	5322
February	1st to 10th	Day	17% 7% 2 7% 5% 5% 5% 4 5% 6% 39%	1949
	11th to 20th	Day	15% 7% 3 6% 4 4 4 4 6% 8% 40%	2048
	21st to end	Day	20% 8% 2 6% 3 4 3 3 5% 6% 38%	1730
March	1st to 10th	Day	23% 8% 3 5% 3 3 3 2 4 5% 39%	4576
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 6% 7% 41%	4773
	21st to end	Day	21% 8% 2 6% 4 3 4 3 5% 6% 37%	6102
April	1st to 10th	Day	20% 8% 2 6% 4 4 3 3 6% 7% 37%	2520
	11th to 20th	Day	19% 6% 2 6% 4 4 4 3 6% 7% 41%	2494
	21st to end	Day	21% 6% 2 5% 4 3 4 3 5% 6% 40%	2622
May	1st to 10th	Day	27% 8% 2 5% 4 4 3 3 5% 7% 31%	7639
	11th to 20th	Day	20% 7% 3 6% 4 4 4 3 5% 6% 37%	8018
	21st to end	Day	24% 7% 2 6% 4 4 5% 4 6% 7% 32%	9060
June	1st to 10th	Day	18% 5% 2 5% 4 5% 5% 4 7% 9% 36%	2940
	11th to 20th	Day	16% 7% 2 6% 5% 4 5% 4 7% 8% 36%	2940
	21st to end	Day	14% 7% 2 6% 5% 4 5% 4 6% 9% 38%	2940
July	1st to 10th	Day	16% 6% 2 6% 4 5% 5% 4 6% 9% 35%	8280
	11th to 20th	Day	11% 6% 2 6% 4 4 5% 5% 7% 11% 39%	8280
	21st to end	Day	16% 7% 2 6% 4 4 5% 4 5% 7% 40%	8993
August	1st to 10th	Day	17% 6% 2 7% 5% 5% 6% 5% 7% 9% 29%	6258
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 4 6% 10% 43%	5488
	21st to end	Day	12% 5% 2 6% 4 4 5% 4 7% 9% 42%	6080
September	1st to 10th	Day	14% 6% 3 6% 4 4 4 4 5% 6% 45%	2520
	11th to 20th	Day	13% 5% 2 5% 3 4 4 3 5% 7% 50%	2384
	21st to end	Day	20% 6% 2 7% 4 4 4 3 5% 6% 39%	2288
October	1st to 10th	Day	21% 6% 2 6% 3 3 3 3 4 5% 43%	2155
	11th to 20th	Day	16% 5% 2 5% 4 3 3 3 5% 8% 46%	1995
	21st to end	Day	20% 6% 2 6% 4 4 3 4 5% 6% 42%	1980
November	1st to 10th	Day	13% 6% 2 6% 4 4 3 2 5% 6% 49%	1851
	11th to 20th	Day	17% 6% 2 4 3 3 3 3 5% 7% 47%	1890
	21st to end	Day	19% 7% 2 5% 3 3 4 3 6% 7% 42%	1848
December	1st to 10th	Day	16% 6% 2 5% 4 4 3 3 5% 7% 45%	2680
	11th to 20th	Day	21% 7% 2 5% 3 3 3 2 5% 5% 45%	3066
	21st to end	Day	19% 9% 4 7% 4 3 3 2 4 6% 39%	4048
January	1st to 10th	Night	15% 7% 2 5% 4 4 4 3 5% 6% 44%	8234
	11th to 20th	Night	16% 9% 2 7% 4 4 4 3 5% 5% 43%	8235
	21st to end	Night	16% 8% 3 6% 4 4 4 3 4 5% 42%	8841
February	1st to 10th	Night	16% 10% 3 6% 4 4 4 3 5% 5% 41%	2669
	11th to 20th	Night	17% 8% 3 5% 4 4 3 3 5% 7% 40%	2458
	21st to end	Night	18% 8% 2 7% 4 4 4 3 4 5% 40%	2076
March	1st to 10th	Night	21% 10% 2 5% 3 3 3 3 4 5% 41%	5484
	11th to 20th	Night	16% 9% 4 6% 4 4 4 3 5% 6% 41%	5389
	21st to end	Night	21% 9% 3 6% 3 3 3 3 4 6% 38%	5072
April	1st to 10th	Night	20% 7% 2 6% 4 4 4 4 5% 6% 37%	2100
	11th to 20th	Night	20% 6% 3 6% 3 4 3 3 5% 6% 40%	2075
	21st to end	Night	19% 7% 3 6% 4 3 3 3 4 5% 43%	1996
May	1st to 10th	Night	26% 11% 3 7% 4 3 3 3 4 6% 30%	5259
	11th to 20th	Night	20% 9% 3 7% 4 3 4 3 5% 7% 34%	4884
	21st to end	Night	23% 9% 3 7% 4 4 4 3 5% 6% 32%	5114
June	1st to 10th	Night	17% 7% 3 5% 5% 4 4 3 5% 6% 41%	1680
	11th to 20th	Night	17% 6% 3 5% 4 4 4 3 5% 10% 40%	1680
	21st to end	Night	13% 7% 3 5% 4 4 4 3 6% 9% 42%	1680
July	1st to 10th	Night	18% 7% 3 6% 4 4 5% 4 5% 9% 35%	4680
	11th to 20th	Night	15% 7% 3 7% 4 4 5% 4 6% 8% 37%	4680
	21st to end	Night	16% 6% 2 5% 4 4 4 4 6% 7% 42%	5084
August	1st to 10th	Night	20% 7% 3 7% 5% 5% 5% 4 6% 7% 32%	3829
	11th to 20th	Night	13% 7% 2 6% 4 5% 5% 4 6% 8% 40%	4556
	21st to end	Night	13% 5% 2 5% 4 3 4 3 6% 7% 49%	5045
September	1st to 10th	Night	15% 7% 2 7% 4 3 4 2 6% 7% 44%	2100
	11th to 20th	Night	13% 6% 2 5% 3 3 3 3 4 6% 52%	2236
	21st to end	Night	20% 7% 3 5% 3 3 4 3 4 5% 42%	2289
October	1st to 10th	Night	19% 7% 3 5% 4 4 4 3 4 7% 42%	2241
	11th to 20th	Night	16% 5% 2 6% 3 3 4 3 4 5% 48%	2405
	21st to end	Night	22% 7% 2 5% 3 3 4 3 5% 5% 42%	2860
November	1st to 10th	Night	12% 6% 2 5% 4 4 4 3 4 6% 49%	2667
	11th to 20th	Night	18% 6% 2 5% 3 2 4 2 4 6% 47%	2730
	21st to end	Night	16% 6% 2 5% 5% 4 3 3 5% 6% 46%	2770
December	1st to 10th	Night	17% 7% 3 5% 3 3 3 3 4 4 48%	4720
	11th to 20th	Night	25% 7% 2 4 3 3 3 3 4 4 42%	5348
	21st to end	Night	19% 10% 3 7% 4 3 3 3 4 4 40%	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	40% 6% 10% 26% 16% 3	4662
	11th to 20th	Day	42% 5% 10% 21% 15% 8%	4680
	21st to end	Day	40% 6% 9% 25% 18% 1	5322
February	1st to 10th	Day	45% 5% 13% 20% 15% 2	1949
	11th to 20th	Day	40% 6% 11% 23% 17% 3	2057
	21st to end	Day	46% 6% 12% 20% 14% 3	1730
March	1st to 10th	Day	46% 5% 11% 16% 12% 10%	4579
	11th to 20th	Day	38% 6% 16% 27% 11% 2	4773
	21st to end	Day	46% 5% 9% 14% 20% 6%	6102
April	1st to 10th	Day	46% 5% 10% 20% 15% 4	2520
	11th to 20th	Day	42% 6% 12% 20% 18% 3	2494
	21st to end	Day	44% 6% 10% 20% 17% 4	2622
May	1st to 10th	Day	51% 8% 13% 16% 12% 1	7651
	11th to 20th	Day	46% 7% 12% 21% 13% 1	8022
	21st to end	Day	48% 8% 12% 19% 12% 1	9061
June	1st to 10th	Day	42% 8% 12% 23% 13% 1	2940
	11th to 20th	Day	41% 8% 14% 22% 13% 1	2940
	21st to end	Day	40% 9% 15% 22% 14% 1	2940
July	1st to 10th	Day	44% 9% 13% 20% 14% 1	8210
	11th to 20th	Day	36% 8% 17% 26% 13% 1	8205
	21st to end	Day	41% 7% 11% 23% 18% 1	8795
August	1st to 10th	Day	47% 9% 17% 18% 9%	6244
	11th to 20th	Day	35% 8% 17% 31% 8%	5524
	21st to end	Day	36% 7% 16% 25% 15% 2	6080
September	1st to 10th	Day	39% 7% 11% 23% 18% 2	2520
	11th to 20th	Day	33% 6% 11% 23% 23% 3	2384
	21st to end	Day	45% 6% 10% 19% 17% 3	2288
October	1st to 10th	Day	35% 7% 10% 18% 24% 6%	3506
	11th to 20th	Day	28% 5% 10% 24% 30% 4	3223
	21st to end	Day	31% 5% 13% 24% 23% 3	3180
November	1st to 10th	Day	37% 5% 12% 23% 21% 3	1851
	11th to 20th	Day	37% 4 11% 23% 21% 3	1890
	21st to end	Day	41% 4 13% 27% 12% 3	1848
December	1st to 10th	Day	39% 5% 16% 27% 12% 1	2680
	11th to 20th	Day	41% 3 15% 19% 18% 3	3066
	21st to end	Day	47% 5% 8% 20% 15% 4	4048
January	1st to 10th	Night	39% 4 11% 25% 18% 2	8234
	11th to 20th	Night	43% 4 11% 19% 16% 6%	8280
	21st to end	Night	44% 4 9% 20% 19% 4	8841
February	1st to 10th	Night	45% 5% 12% 23% 13% 2	2669
	11th to 20th	Night	44% 4 10% 20% 18% 4	2460
	21st to end	Night	46% 4 8% 23% 14% 4	2076
March	1st to 10th	Night	45% 5% 11% 18% 14% 7%	5494
	11th to 20th	Night	43% 6% 15% 21% 11% 4	5390
	21st to end	Night	48% 4 7% 12% 24% 5%	5072
April	1st to 10th	Night	46% 6% 10% 19% 14% 4	2100
	11th to 20th	Night	44% 5% 11% 19% 20% 1	2075
	21st to end	Night	44% 5% 9% 21% 17% 4	1996
May	1st to 10th	Night	54% 6% 13% 14% 12% 1	5265
	11th to 20th	Night	48% 8% 12% 19% 10% 2	4885
	21st to end	Night	53% 5% 12% 21% 8% 1	5115
June	1st to 10th	Night	44% 6% 10% 20% 18% 1	1680
	11th to 20th	Night	41% 8% 15% 24% 11% 1	1680
	21st to end	Night	39% 7% 13% 25% 14% 1	1680
July	1st to 10th	Night	46% 8% 14% 19% 12% 1	4640
	11th to 20th	Night	43% 7% 14% 23% 12% 1	4632
	21st to end	Night	39% 7% 13% 24% 16% 1	4967
August	1st to 10th	Night	49% 9% 14% 17% 10% 1	3819
	11th to 20th	Night	40% 8% 16% 30% 7%	4586
	21st to end	Night	33% 6% 14% 31% 15% 1	5045
September	1st to 10th	Night	40% 6% 10% 25% 17% 1	2100
	11th to 20th	Night	34% 6% 10% 23% 25% 2	2236
	21st to end	Night	44% 6% 8% 20% 19% 2	2289
October	1st to 10th	Night	37% 6% 12% 22% 20% 3	3670
	11th to 20th	Night	26% 5% 9% 27% 29% 4	3916
	21st to end	Night	32% 4 14% 28% 20% 3	4610
November	1st to 10th	Night	35% 5% 12% 23% 21% 4	2667
	11th to 20th	Night	39% 3 10% 23% 20% 4	2730
	21st to end	Night	39% 4 13% 29% 13% 2	2770
December	1st to 10th	Night	39% 4 12% 30% 13% 2	4720
	11th to 20th	Night	46% 4 11% 18% 18% 3	5348
	21st to end	Night	46% 4 10% 19% 16% 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	26% 28% 27% 16% 2	220
	11th to 20th	Day	23% 34% 30% 12%	220
	21st to end	Day	23% 30% 33% 9% 4 1	278
February	1st to 10th	Day	25% 26% 35% 12% 1	389
	11th to 20th	Day	24% 26% 37% 11% 1	536
	21st to end	Day	26% 26% 32% 12% 3	446
March	1st to 10th	Day	23% 24% 36% 14% 3	540
	11th to 20th	Day	22% 27% 34% 14% 3 1	540
	21st to end	Day	28% 23% 35% 11% 3 1	594
April	1st to 10th	Day	27% 26% 29% 12% 5% 1	540
	11th to 20th	Day	26% 23% 32% 13% 5% 1	532
	21st to end	Day	27% 19% 34% 15% 4 1	540
May	1st to 10th	Day	29% 21% 32% 12% 5% 1	543
	11th to 20th	Day	20% 17% 37% 19% 5% 1	567
	21st to end	Day	21% 13% 29% 25% 9% 2	617
June	1st to 10th	Day	18% 13% 31% 25% 11% 2	570
	11th to 20th	Day	18% 13% 32% 26% 10% 1	570
	21st to end	Day	15% 10% 36% 26% 11% 2	570
July	1st to 10th	Day	16% 6% 30% 30% 15% 3	565
	11th to 20th	Day	13% 7% 30% 30% 17% 3	564
	21st to end	Day	13% 8% 33% 34% 10% 2	620
August	1st to 10th	Day	14% 7% 28% 35% 12% 5%	566
	11th to 20th	Day	14% 6% 27% 33% 15% 5%	559
	21st to end	Day	11% 11% 33% 26% 14% 6%	627
September	1st to 10th	Day	16% 11% 30% 22% 17% 4	570
	11th to 20th	Day	15% 7% 30% 28% 13% 7%	570
	21st to end	Day	23% 12% 31% 22% 9% 3	562
October	1st to 10th	Day	24% 10% 27% 21% 14% 5%	530
	11th to 20th	Day	18% 20% 29% 23% 9% 2	527
	21st to end	Day	24% 17% 32% 19% 7% 1	462
November	1st to 10th	Day	17% 17% 31% 23% 10% 2	425
	11th to 20th	Day	22% 26% 28% 20% 4	430
	21st to end	Day	25% 22% 29% 19% 5%	388
December	1st to 10th	Day	27% 18% 33% 17% 5%	220
	11th to 20th	Day	32% 25% 27% 13% 3	220
	21st to end	Day	24% 22% 33% 16% 4 1	242
January	1st to 10th	Night	22% 21% 36% 18% 3	840
	11th to 20th	Night	26% 20% 33% 19% 2	840
	21st to end	Night	21% 20% 38% 18% 2	924
February	1st to 10th	Night	21% 19% 37% 21% 2	840
	11th to 20th	Night	25% 20% 37% 16% 1	823
	21st to end	Night	23% 22% 36% 16% 3	692
March	1st to 10th	Night	24% 19% 33% 20% 3	840
	11th to 20th	Night	22% 18% 37% 20% 3 1	840
	21st to end	Night	23% 20% 38% 16% 4	924
April	1st to 10th	Night	24% 18% 34% 20% 3	840
	11th to 20th	Night	23% 16% 36% 22% 4	831
	21st to end	Night	21% 16% 37% 21% 4 1	736
May	1st to 10th	Night	26% 12% 34% 22% 6%	630
	11th to 20th	Night	22% 12% 37% 23% 5%	505
	21st to end	Night	23% 7% 25% 36% 8% 1	455
June	1st to 10th	Night	19% 7% 30% 33% 10% 1	420
	11th to 20th	Night	18% 8% 29% 34% 11%	420
	21st to end	Night	16% 6% 25% 42% 10%	420
July	1st to 10th	Night	15% 5% 23% 40% 17% 1	410
	11th to 20th	Night	15% 3 21% 43% 16% 1	408
	21st to end	Night	15% 4 23% 44% 14% 1	460
August	1st to 10th	Night	12% 3 27% 40% 16% 1	490
	11th to 20th	Night	15% 4 22% 39% 19% 2	829
	21st to end	Night	14% 6% 24% 36% 18% 2	924
September	1st to 10th	Night	18% 6% 26% 33% 15% 2	840
	11th to 20th	Night	16% 6% 24% 32% 19% 4	840
	21st to end	Night	23% 8% 25% 29% 14% 1	833
October	1st to 10th	Night	21% 10% 28% 26% 14% 2	800
	11th to 20th	Night	18% 14% 32% 27% 9% 1	800
	21st to end	Night	25% 12% 34% 21% 7%	880
November	1st to 10th	Night	17% 13% 34% 26% 9% 1	820
	11th to 20th	Night	22% 17% 35% 19% 5% 1	840
	21st to end	Night	21% 18% 31% 24% 5% 1	840
December	1st to 10th	Night	25% 17% 32% 20% 5% 1	840
	11th to 20th	Night	25% 19% 33% 20% 3	840
	21st to end	Night	26% 19% 33% 20% 2	924

Page generated at 2026-09-26 04:18:39. Version ac07

Copyright © 2026 Attilla Danko.