Fishcreek Rd Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fishcreek Rd Observing Site 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	16% 11% 4 10% 5% 5% 5% 4 5% 7% 29%	137127
	Night	16% 12% 4 10% 5% 4 4 3 5% 6% 30%	134874
Transparency	Day	53% 5% 11% 19% 10% 1	140772
	Night	54% 5% 11% 18% 11% 1	139301
Seeing	Day	22% 17% 28% 19% 11% 3	16649
	Night	21% 13% 28% 26% 11% 1	26524

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	16% 21% 7% 24% 6% 4 3 2 3 4 10%	5258
	11th to 20th	Day	11% 21% 8% 20% 10% 8% 5% 2 3 3 11%	5280
	21st to end	Day	19% 17% 8% 13% 10% 8% 4 3 3 4 12%	5780
February	1st to 10th	Day	17% 17% 6% 11% 7% 5% 4 3 4 5% 20%	1890
	11th to 20th	Day	15% 13% 7% 15% 8% 5% 5% 3 4 5% 19%	1896
	21st to end	Day	17% 15% 5% 13% 6% 4 4 4 5% 6% 22%	1730
March	1st to 10th	Day	18% 12% 7% 12% 5% 3 4 3 5% 6% 26%	4946
	11th to 20th	Day	12% 11% 5% 11% 5% 4 4 3 4 6% 35%	5090
	21st to end	Day	21% 12% 5% 9% 5% 4 4 3 4 5% 27%	5586
April	1st to 10th	Day	16% 13% 4 8% 5% 5% 4 3 5% 7% 29%	2357
	11th to 20th	Day	18% 12% 3 8% 5% 4 5% 3 5% 6% 31%	2656
	21st to end	Day	19% 11% 3 7% 5% 4 4 3 5% 6% 33%	2730
May	1st to 10th	Day	21% 10% 3 8% 5% 5% 5% 4 6% 6% 28%	7616
	11th to 20th	Day	17% 9% 3 7% 4 5% 4 4 6% 8% 32%	7626
	21st to end	Day	19% 7% 3 6% 4 4 4 4 6% 6% 36%	8510
June	1st to 10th	Day	14% 6% 3 7% 5% 5% 5% 4 7% 8% 38%	2940
	11th to 20th	Day	13% 7% 3 8% 5% 5% 5% 4 6% 8% 36%	2870
	21st to end	Day	12% 5% 2 5% 5% 5% 5% 5% 7% 10% 38%	2793
July	1st to 10th	Day	8% 6% 3 7% 5% 4 5% 4 7% 10% 41%	5900
	11th to 20th	Day	11% 6% 2 6% 5% 6% 5% 5% 7% 10% 36%	5900
	21st to end	Day	11% 6% 2 7% 5% 5% 5% 4 6% 9% 39%	6424
August	1st to 10th	Day	12% 8% 3 7% 5% 5% 6% 4 7% 9% 34%	4234
	11th to 20th	Day	12% 6% 2 7% 5% 5% 6% 5% 8% 9% 35%	4174
	21st to end	Day	9% 5% 2 7% 5% 5% 6% 5% 7% 10% 39%	4585
September	1st to 10th	Day	13% 6% 2 6% 4 5% 4 3 5% 7% 44%	2302
	11th to 20th	Day	10% 6% 2 7% 5% 4 5% 4 5% 8% 44%	2200
	21st to end	Day	20% 9% 3 6% 3 4 4 3 4 7% 37%	2200
October	1st to 10th	Day	14% 7% 2 7% 4 4 4 4 5% 7% 41%	2060
	11th to 20th	Day	20% 10% 3 8% 4 4 4 3 5% 6% 34%	2000
	21st to end	Day	22% 11% 4 9% 4 4 5% 3 5% 6% 28%	2200
November	1st to 10th	Day	13% 10% 4 8% 5% 4 4 4 5% 7% 37%	1857
	11th to 20th	Day	18% 16% 3 8% 5% 4 4 3 5% 6% 27%	1853
	21st to end	Day	19% 17% 8% 10% 5% 4 5% 4 5% 6% 18%	1680
December	1st to 10th	Day	18% 16% 7% 17% 6% 4 4 3 4 4 17%	2680
	11th to 20th	Day	22% 21% 7% 12% 5% 3 3 3 3 5% 16%	3070
	21st to end	Day	26% 22% 7% 13% 5% 4 3 2 3 4 10%	4254
January	1st to 10th	Night	15% 19% 8% 25% 6% 4 3 2 3 3 10%	7635
	11th to 20th	Night	11% 20% 10% 19% 9% 6% 6% 3 3 3 11%	7680
	21st to end	Night	18% 18% 6% 12% 6% 6% 5% 2 4 5% 18%	8401
February	1st to 10th	Night	19% 16% 5% 12% 7% 4 4 3 5% 4 21%	2730
	11th to 20th	Night	16% 14% 5% 13% 8% 5% 5% 4 4 5% 20%	2607
	21st to end	Night	20% 14% 4 11% 6% 4 4 3 4 5% 24%	2076
March	1st to 10th	Night	22% 14% 4 9% 4 3 3 2 3 5% 31%	5125
	11th to 20th	Night	14% 10% 4 7% 4 4 5% 3 5% 6% 37%	5090
	21st to end	Night	18% 12% 4 8% 5% 4 4 4 4 5% 32%	5588
April	1st to 10th	Night	18% 13% 4 8% 5% 4 4 4 5% 7% 29%	2263
	11th to 20th	Night	16% 11% 3 7% 5% 4 5% 4 6% 6% 33%	1930
	21st to end	Night	14% 10% 2 8% 4 5% 5% 3 6% 7% 36%	1890
May	1st to 10th	Night	25% 9% 3 7% 5% 4 4 4 5% 6% 28%	5237
	11th to 20th	Night	17% 9% 3 6% 4 3 4 4 5% 7% 39%	5234
	21st to end	Night	21% 7% 2 5% 4 4 4 3 5% 8% 37%	5624
June	1st to 10th	Night	9% 7% 2 6% 6% 5% 5% 5% 5% 7% 43%	1680
	11th to 20th	Night	11% 6% 2 7% 5% 5% 5% 5% 7% 8% 41%	1640
	21st to end	Night	11% 5% 2 6% 5% 5% 4 4 9% 10% 40%	1600
July	1st to 10th	Night	10% 6% 2 6% 4 4 4 4 6% 9% 45%	4057
	11th to 20th	Night	11% 5% 2 6% 4 5% 5% 5% 7% 9% 42%	4057
	21st to end	Night	9% 6% 2 6% 4 4 4 3 6% 8% 47%	4427
August	1st to 10th	Night	11% 8% 3 7% 5% 5% 5% 4 6% 7% 40%	2915
	11th to 20th	Night	15% 8% 2 6% 4 4 4 3 4 6% 44%	2875
	21st to end	Night	8% 6% 2 7% 5% 5% 5% 4 7% 8% 43%	3279
September	1st to 10th	Night	11% 6% 2 5% 4 4 4 3 5% 8% 47%	2094
	11th to 20th	Night	9% 5% 2 6% 4 3 3 3 5% 9% 52%	2200
	21st to end	Night	16% 7% 3 7% 5% 4 4 3 5% 7% 40%	2200
October	1st to 10th	Night	14% 5% 2 5% 4 3 4 4 6% 7% 45%	2338
	11th to 20th	Night	18% 7% 3 8% 4 4 5% 3 5% 7% 36%	2400
	21st to end	Night	22% 10% 2 7% 4 3 4 4 4 6% 33%	2640
November	1st to 10th	Night	14% 9% 3 6% 3 5% 5% 4 5% 6% 40%	2656
	11th to 20th	Night	17% 15% 4 8% 5% 5% 4 3 5% 6% 28%	2763
	21st to end	Night	20% 16% 5% 8% 5% 4 4 3 5% 6% 23%	2940
December	1st to 10th	Night	16% 17% 7% 12% 6% 5% 5% 3 4 6% 19%	4720
	11th to 20th	Night	19% 21% 8% 12% 5% 3 3 3 4 4 18%	5345
	21st to end	Night	25% 20% 6% 12% 5% 4 4 3 4 5% 13%	6938

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	80% 4 8% 6% 2	5259
	11th to 20th	Day	80% 3 7% 6% 4	5280
	21st to end	Day	78% 3 6% 10% 3	5780
February	1st to 10th	Day	67% 4 9% 13% 6%	1890
	11th to 20th	Day	68% 5% 8% 13% 6%	1905
	21st to end	Day	63% 5% 11% 13% 6% 1	1730
March	1st to 10th	Day	59% 4 11% 19% 6%	4946
	11th to 20th	Day	51% 5% 13% 24% 6% 1	5090
	21st to end	Day	58% 4 8% 17% 11% 1	5586
April	1st to 10th	Day	54% 6% 12% 16% 11% 1	2357
	11th to 20th	Day	52% 6% 12% 16% 12% 2	2656
	21st to end	Day	51% 5% 11% 21% 10% 2	2730
May	1st to 10th	Day	55% 6% 9% 19% 8% 3	7651
	11th to 20th	Day	48% 6% 12% 22% 11% 1	7630
	21st to end	Day	46% 6% 10% 17% 17% 4	8525
June	1st to 10th	Day	43% 7% 12% 24% 14% 1	2940
	11th to 20th	Day	44% 7% 14% 20% 14% 1	2870
	21st to end	Day	38% 8% 14% 23% 16% 1	2793
July	1st to 10th	Day	37% 6% 12% 29% 15% 2	5835
	11th to 20th	Day	40% 7% 14% 24% 15% 1	5831
	21st to end	Day	39% 7% 11% 21% 20% 2	6240
August	1st to 10th	Day	45% 7% 14% 22% 11% 1	4221
	11th to 20th	Day	41% 7% 12% 28% 10% 1	4213
	21st to end	Day	38% 7% 14% 29% 10% 2	4585
September	1st to 10th	Day	40% 5% 14% 22% 16% 3	2302
	11th to 20th	Day	36% 7% 14% 25% 16% 1	2200
	21st to end	Day	47% 5% 10% 22% 15% 1	2200
October	1st to 10th	Day	33% 5% 13% 29% 19% 1	3359
	11th to 20th	Day	46% 5% 11% 20% 15% 4	3240
	21st to end	Day	44% 4 13% 23% 16% 1	3538
November	1st to 10th	Day	47% 6% 11% 23% 13% 1	1857
	11th to 20th	Day	58% 5% 10% 17% 7% 3	1853
	21st to end	Day	67% 6% 9% 12% 5%	1680
December	1st to 10th	Day	72% 4 11% 10% 2	2680
	11th to 20th	Day	73% 4 8% 12% 2	3066
	21st to end	Day	81% 3 7% 7% 2	4254
January	1st to 10th	Night	80% 3 6% 8% 3	7636
	11th to 20th	Night	79% 4 7% 7% 3	7680
	21st to end	Night	70% 3 9% 12% 5%	8401
February	1st to 10th	Night	66% 5% 9% 15% 5%	2730
	11th to 20th	Night	66% 5% 9% 15% 5%	2609
	21st to end	Night	63% 4 9% 14% 8% 1	2076
March	1st to 10th	Night	57% 3 12% 18% 8%	5125
	11th to 20th	Night	44% 6% 16% 23% 9% 1	5090
	21st to end	Night	53% 5% 9% 19% 13% 1	5588
April	1st to 10th	Night	54% 6% 11% 16% 12% 1	2263
	11th to 20th	Night	49% 7% 11% 17% 13% 2	1930
	21st to end	Night	46% 6% 11% 19% 15% 2	1890
May	1st to 10th	Night	57% 6% 9% 15% 10% 4	5264
	11th to 20th	Night	45% 6% 10% 24% 13% 1	5235
	21st to end	Night	45% 6% 12% 21% 15% 2	5633
June	1st to 10th	Night	40% 7% 10% 24% 17% 3	1680
	11th to 20th	Night	39% 7% 14% 20% 17% 3	1640
	21st to end	Night	36% 9% 13% 24% 16% 2	1600
July	1st to 10th	Night	36% 6% 13% 25% 18% 3	4014
	11th to 20th	Night	37% 8% 13% 27% 14% 1	4006
	21st to end	Night	34% 6% 12% 20% 26% 2	4297
August	1st to 10th	Night	41% 7% 12% 24% 14% 2	2904
	11th to 20th	Night	41% 5% 10% 30% 13% 1	2902
	21st to end	Night	37% 6% 13% 28% 14% 2	3279
September	1st to 10th	Night	35% 6% 11% 27% 17% 4	2094
	11th to 20th	Night	29% 6% 14% 28% 22% 2	2200
	21st to end	Night	44% 6% 10% 20% 18% 1	2200
October	1st to 10th	Night	32% 5% 10% 29% 23% 1	3819
	11th to 20th	Night	43% 5% 11% 21% 18% 3	3899
	21st to end	Night	40% 4 12% 27% 16% 1	4252
November	1st to 10th	Night	42% 7% 12% 23% 14% 2	2656
	11th to 20th	Night	57% 5% 10% 17% 8% 3	2763
	21st to end	Night	63% 4 12% 16% 5%	2940
December	1st to 10th	Night	67% 6% 11% 12% 3	4720
	11th to 20th	Night	71% 4 10% 13% 2	5348
	21st to end	Night	75% 4 10% 9% 1	6938

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	32% 25% 30% 9% 3	330
	11th to 20th	Day	35% 28% 29% 6% 2	330
	21st to end	Day	30% 33% 28% 7% 2	363
February	1st to 10th	Day	30% 27% 33% 8% 1 1	330
	11th to 20th	Day	30% 30% 32% 8% 1	330
	21st to end	Day	31% 32% 33% 4	273
March	1st to 10th	Day	26% 24% 33% 13% 4	489
	11th to 20th	Day	31% 18% 35% 11% 4 1	540
	21st to end	Day	31% 23% 27% 14% 3	594
April	1st to 10th	Day	27% 25% 27% 15% 5% 1	540
	11th to 20th	Day	30% 20% 25% 16% 7% 3	532
	21st to end	Day	26% 19% 32% 17% 6% 1	540
May	1st to 10th	Day	27% 21% 29% 16% 6% 2	543
	11th to 20th	Day	22% 14% 33% 21% 7% 3	567
	21st to end	Day	18% 12% 29% 22% 15% 4	617
June	1st to 10th	Day	15% 13% 33% 27% 10% 2	570
	11th to 20th	Day	17% 13% 26% 31% 11% 3	550
	21st to end	Day	14% 10% 32% 26% 14% 4	530
July	1st to 10th	Day	12% 6% 24% 29% 21% 8%	525
	11th to 20th	Day	13% 8% 27% 27% 19% 6%	524
	21st to end	Day	12% 6% 27% 30% 19% 7%	576
August	1st to 10th	Day	13% 6% 23% 28% 23% 7%	526
	11th to 20th	Day	14% 9% 23% 27% 18% 9%	519
	21st to end	Day	11% 6% 24% 28% 22% 10%	583
September	1st to 10th	Day	14% 10% 22% 25% 20% 8%	530
	11th to 20th	Day	8% 5% 19% 30% 26% 11%	530
	21st to end	Day	24% 11% 23% 22% 14% 5%	530
October	1st to 10th	Day	14% 10% 31% 21% 21% 3	530
	11th to 20th	Day	22% 18% 34% 16% 7% 2	530
	21st to end	Day	30% 19% 29% 18% 3	583
November	1st to 10th	Day	20% 24% 34% 12% 9% 1	335
	11th to 20th	Day	31% 26% 26% 13% 3 1	311
	21st to end	Day	28% 26% 35% 10% 1	220
December	1st to 10th	Day	27% 25% 33% 10% 3 1	220
	11th to 20th	Day	29% 29% 29% 11% 2	220
	21st to end	Day	36% 26% 27% 10% 1	289
January	1st to 10th	Night	26% 23% 34% 14% 3	840
	11th to 20th	Night	30% 25% 29% 14% 3	840
	21st to end	Night	28% 21% 30% 18% 2	924
February	1st to 10th	Night	28% 20% 30% 20% 2	840
	11th to 20th	Night	26% 21% 33% 17% 2	823
	21st to end	Night	28% 22% 35% 15% 2	692
March	1st to 10th	Night	23% 19% 35% 20% 4	840
	11th to 20th	Night	24% 17% 31% 21% 5% 1	840
	21st to end	Night	24% 15% 33% 21% 6%	924
April	1st to 10th	Night	25% 16% 33% 22% 5%	840
	11th to 20th	Night	22% 14% 36% 20% 8%	686
	21st to end	Night	18% 14% 34% 28% 6%	630
May	1st to 10th	Night	21% 11% 28% 31% 8% 1	630
	11th to 20th	Night	18% 9% 27% 35% 9% 1	621
	21st to end	Night	15% 4 25% 36% 18% 2	636
June	1st to 10th	Night	11% 5% 32% 39% 14%	420
	11th to 20th	Night	13% 5% 27% 41% 13% 1	410
	21st to end	Night	12% 6% 27% 37% 18% 1	400
July	1st to 10th	Night	9% 4 16% 41% 27% 3	584
	11th to 20th	Night	8% 4 21% 38% 24% 4	582
	21st to end	Night	9% 5% 16% 42% 27% 2	657
August	1st to 10th	Night	9% 3 16% 43% 26% 3	597
	11th to 20th	Night	11% 3 16% 38% 29% 3	594
	21st to end	Night	11% 2 20% 35% 29% 3	690
September	1st to 10th	Night	13% 6% 18% 35% 24% 4	800
	11th to 20th	Night	10% 3 17% 37% 28% 5%	800
	21st to end	Night	18% 9% 22% 30% 17% 4	800
October	1st to 10th	Night	16% 8% 26% 28% 20% 2	800
	11th to 20th	Night	23% 12% 29% 26% 9% 1	800
	21st to end	Night	26% 15% 29% 24% 5%	880
November	1st to 10th	Night	19% 14% 31% 25% 10%	820
	11th to 20th	Night	26% 19% 30% 19% 6% 1	840
	21st to end	Night	30% 18% 31% 15% 5%	840
December	1st to 10th	Night	30% 18% 32% 16% 3	840
	11th to 20th	Night	27% 22% 32% 17% 2	840
	21st to end	Night	30% 17% 34% 16% 2	924

Page generated at 2026-06-13 02:31:40. Version ac07

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