Fall River State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fall River State Park clear sky chart from 2005-11-06 to 2024-11-08.

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	11% 6% 2 6% 4 4 4 3 5% 7% 48%	101317
	Night	10% 6% 2 5% 3 3 4 3 5% 7% 52%	97890
Transparency	Day	34% 6% 12% 26% 19% 4	105007
	Night	31% 5% 12% 26% 21% 5%	102327
Seeing	Day	13% 9% 27% 29% 18% 5%	15579
	Night	13% 9% 31% 34% 13% 1	25410

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	12% 8% 3 8% 6% 4 4 3 4 6% 42%	2847
	11th to 20th	Day	10% 9% 3 7% 7% 7% 4 3 5% 6% 39%	2850
	21st to end	Day	14% 14% 4 7% 3 3 3 2 3 5% 41%	3135
February	1st to 10th	Day	15% 9% 3 7% 5% 3 3 2 3 6% 44%	1710
	11th to 20th	Day	11% 7% 3 8% 4 4 4 3 5% 6% 46%	1771
	21st to end	Day	11% 8% 3 6% 3 4 5% 4 5% 7% 44%	1579
March	1st to 10th	Day	13% 8% 2 5% 3 3 2 2 2 5% 53%	3436
	11th to 20th	Day	10% 5% 1 3 2 3 3 3 4 7% 57%	3480
	21st to end	Day	14% 9% 4 7% 5% 4 4 3 5% 6% 40%	3814
April	1st to 10th	Day	11% 7% 2 5% 4 3 3 3 5% 8% 48%	2109
	11th to 20th	Day	14% 8% 2 6% 4 4 3 3 5% 6% 44%	2273
	21st to end	Day	18% 8% 3 5% 4 4 3 4 5% 5% 41%	2470
May	1st to 10th	Day	19% 9% 3 7% 5% 4 4 3 4 5% 38%	4082
	11th to 20th	Day	12% 7% 2 6% 4 4 4 4 5% 7% 45%	4082
	21st to end	Day	13% 7% 2 6% 5% 4 5% 4 6% 8% 41%	4477
June	1st to 10th	Day	6% 4 1 5% 5% 4 5% 4 6% 10% 50%	2470
	11th to 20th	Day	8% 4 2 4 4 4 5% 3 6% 9% 51%	2470
	21st to end	Day	6% 3 2 3 4 3 4 4 6% 8% 57%	2470
July	1st to 10th	Day	10% 5% 2 6% 4 5% 5% 4 7% 8% 44%	4120
	11th to 20th	Day	6% 3 2 4 4 4 4 4 6% 9% 53%	4120
	21st to end	Day	6% 4 2 5% 5% 5% 6% 5% 8% 10% 44%	4465
August	1st to 10th	Day	6% 4 2 5% 4 3 5% 4 6% 8% 54%	4104
	11th to 20th	Day	7% 4 2 7% 4 5% 4 4 5% 8% 49%	4041
	21st to end	Day	5% 3 1 4 3 4 4 3 5% 8% 60%	4354
September	1st to 10th	Day	12% 4 1 5% 4 2 4 3 4 6% 54%	2153
	11th to 20th	Day	11% 5% 2 6% 3 4 4 3 4 7% 52%	2090
	21st to end	Day	10% 4 1 4 3 3 3 3 4 6% 58%	2090
October	1st to 10th	Day	9% 6% 2 6% 4 3 4 3 5% 6% 53%	1963
	11th to 20th	Day	10% 4 1 3 2 2 3 3 5% 6% 61%	1900
	21st to end	Day	15% 6% 2 4 3 3 3 2 4 5% 53%	2090
November	1st to 10th	Day	10% 6% 1 4 2 2 3 3 4 6% 58%	1876
	11th to 20th	Day	9% 5% 1 4 3 4 3 2 4 6% 58%	1710
	21st to end	Day	14% 6% 2 4 3 2 3 2 4 5% 56%	1710
December	1st to 10th	Day	10% 7% 2 5% 4 4 4 4 4 7% 50%	1710
	11th to 20th	Day	12% 8% 3 6% 5% 5% 4 3 4 5% 46%	2161
	21st to end	Day	14% 11% 7% 10% 5% 4 4 3 5% 6% 31%	3135
January	1st to 10th	Night	10% 9% 3 9% 4 3 4 2 4 5% 47%	4108
	11th to 20th	Night	8% 7% 2 6% 6% 6% 5% 4 5% 5% 46%	4120
	21st to end	Night	18% 11% 3 5% 3 2 2 2 3 4 46%	4532
February	1st to 10th	Night	11% 9% 3 6% 5% 4 3 3 5% 6% 45%	2470
	11th to 20th	Night	12% 7% 3 6% 3 4 4 3 4 6% 49%	2310
	21st to end	Night	12% 6% 3 5% 3 2 3 3 4 7% 52%	1873
March	1st to 10th	Night	12% 7% 2 4 3 3 3 2 4 5% 55%	3419
	11th to 20th	Night	9% 4 1 4 3 3 4 3 4 6% 59%	3480
	21st to end	Night	13% 7% 3 5% 4 4 4 4 5% 6% 45%	3817
April	1st to 10th	Night	10% 4 2 5% 4 3 3 3 6% 6% 53%	2071
	11th to 20th	Night	12% 6% 2 6% 4 3 3 3 4 7% 50%	1852
	21st to end	Night	16% 6% 2 5% 5% 3 3 3 5% 5% 48%	1710
May	1st to 10th	Night	17% 9% 2 7% 3 3 3 2 4 7% 42%	2823
	11th to 20th	Night	15% 6% 2 5% 3 3 4 3 4 7% 47%	2823
	21st to end	Night	11% 4 1 4 3 3 3 3 5% 9% 53%	3090
June	1st to 10th	Night	5% 3 2 4 3 4 5% 4 7% 9% 54%	1710
	11th to 20th	Night	3 4 2 4 3 3 4 5% 6% 12% 52%	1710
	21st to end	Night	6% 2 2 4 3 4 4 4 6% 8% 58%	1710
July	1st to 10th	Night	7% 5% 2 6% 4 4 4 3 6% 8% 52%	2850
	11th to 20th	Night	3 2 1 4 3 4 4 4 6% 11% 56%	2850
	21st to end	Night	6% 4 2 6% 4 4 5% 5% 8% 10% 46%	3098
August	1st to 10th	Night	3 2 1 3 4 4 4 4 6% 9% 58%	2836
	11th to 20th	Night	7% 4 2 5% 4 4 4 5% 6% 8% 52%	2798
	21st to end	Night	3 2 1 3 3 3 4 3 4 8% 65%	3307
September	1st to 10th	Night	10% 3 1 4 3 3 2 3 4 5% 60%	2023
	11th to 20th	Night	9% 4 1 4 3 3 5% 4 6% 6% 53%	2090
	21st to end	Night	7% 2 2 4 2 4 3 3 5% 6% 61%	2090
October	1st to 10th	Night	10% 4 2 5% 3 3 3 3 4 5% 59%	2196
	11th to 20th	Night	11% 4 1 3 3 3 2 2 4 6% 61%	2280
	21st to end	Night	13% 5% 2 4 3 3 3 3 4 5% 56%	2508
November	1st to 10th	Night	9% 4 1 4 3 2 3 2 4 5% 62%	2358
	11th to 20th	Night	9% 6% 1 4 3 3 4 3 4 7% 57%	2470
	21st to end	Night	13% 7% 2 4 3 2 3 3 3 5% 55%	2470
December	1st to 10th	Night	10% 6% 2 5% 3 3 3 3 5% 7% 52%	2470
	11th to 20th	Night	10% 7% 2 6% 4 4 3 3 4 6% 52%	3036
	21st to end	Night	17% 8% 4 8% 4 4 4 3 4 6% 37%	4532

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	42% 6% 11% 24% 16% 1	2848
	11th to 20th	Day	45% 6% 13% 22% 10% 4	2850
	21st to end	Day	48% 3 10% 20% 17% 1	3135
February	1st to 10th	Day	44% 5% 11% 25% 11% 4	1710
	11th to 20th	Day	38% 6% 12% 26% 15% 4	1780
	21st to end	Day	39% 5% 9% 22% 17% 8%	1579
March	1st to 10th	Day	36% 4 6% 22% 27% 6%	3436
	11th to 20th	Day	27% 5% 13% 28% 23% 3	3480
	21st to end	Day	43% 8% 12% 26% 10% 2	3814
April	1st to 10th	Day	34% 6% 14% 24% 19% 5%	2109
	11th to 20th	Day	41% 5% 11% 23% 17% 4	2273
	21st to end	Day	44% 6% 10% 26% 13% 1	2470
May	1st to 10th	Day	49% 6% 9% 19% 14% 3	4120
	11th to 20th	Day	36% 9% 13% 26% 16%	4086
	21st to end	Day	39% 9% 12% 22% 16% 3	4489
June	1st to 10th	Day	27% 10% 17% 27% 16% 2	2470
	11th to 20th	Day	30% 6% 12% 29% 19% 2	2470
	21st to end	Day	22% 6% 17% 28% 21% 5%	2470
July	1st to 10th	Day	35% 7% 12% 23% 19% 4	4056
	11th to 20th	Day	26% 7% 12% 33% 19% 2	4051
	21st to end	Day	29% 9% 19% 28% 15% 1	4325
August	1st to 10th	Day	27% 6% 14% 25% 23% 5%	4090
	11th to 20th	Day	33% 6% 16% 25% 17% 2	4080
	21st to end	Day	23% 5% 16% 37% 14% 5%	4353
September	1st to 10th	Day	31% 6% 12% 24% 20% 7%	2153
	11th to 20th	Day	32% 5% 11% 26% 23% 3	2090
	21st to end	Day	29% 5% 9% 22% 29% 6%	2090
October	1st to 10th	Day	21% 4 8% 17% 40% 11%	3262
	11th to 20th	Day	15% 3 6% 31% 33% 12%	3140
	21st to end	Day	27% 3 8% 27% 27% 7%	3428
November	1st to 10th	Day	28% 5% 9% 30% 23% 6%	1876
	11th to 20th	Day	28% 4 10% 27% 26% 5%	1710
	21st to end	Day	33% 3 10% 27% 24% 3	1710
December	1st to 10th	Day	36% 5% 9% 32% 17% 2	1710
	11th to 20th	Day	40% 6% 8% 26% 17% 3	2159
	21st to end	Day	52% 6% 11% 19% 10% 2	3135
January	1st to 10th	Night	38% 5% 10% 29% 15% 3	4108
	11th to 20th	Night	36% 7% 12% 25% 17% 2	4120
	21st to end	Night	43% 3 12% 23% 17% 2	4532
February	1st to 10th	Night	41% 4 13% 24% 15% 4	2470
	11th to 20th	Night	37% 4 11% 26% 18% 4	2311
	21st to end	Night	33% 4 9% 24% 20% 9%	1873
March	1st to 10th	Night	32% 5% 8% 24% 23% 7%	3419
	11th to 20th	Night	26% 6% 10% 25% 30% 3	3480
	21st to end	Night	38% 7% 15% 26% 12% 1	3817
April	1st to 10th	Night	30% 6% 11% 23% 23% 7%	2071
	11th to 20th	Night	35% 5% 13% 23% 20% 5%	1852
	21st to end	Night	37% 6% 13% 23% 18% 4	1710
May	1st to 10th	Night	42% 8% 12% 20% 14% 4	2850
	11th to 20th	Night	37% 8% 13% 26% 15% 1	2824
	21st to end	Night	28% 8% 17% 26% 20% 2	3099
June	1st to 10th	Night	25% 9% 18% 29% 17% 2	1710
	11th to 20th	Night	23% 8% 16% 30% 20% 4	1710
	21st to end	Night	23% 7% 14% 30% 21% 5%	1710
July	1st to 10th	Night	29% 6% 14% 26% 21% 4	2805
	11th to 20th	Night	20% 5% 13% 36% 23% 3	2796
	21st to end	Night	29% 9% 19% 29% 13% 1	2999
August	1st to 10th	Night	20% 6% 15% 30% 19% 9%	2826
	11th to 20th	Night	29% 7% 15% 27% 20% 3	2825
	21st to end	Night	18% 5% 14% 38% 20% 5%	3307
September	1st to 10th	Night	26% 5% 11% 27% 21% 10%	2023
	11th to 20th	Night	30% 6% 11% 23% 24% 6%	2090
	21st to end	Night	23% 5% 9% 26% 31% 7%	2090
October	1st to 10th	Night	17% 3 7% 14% 45% 14%	3664
	11th to 20th	Night	18% 3 5% 24% 34% 15%	3779
	21st to end	Night	26% 3 8% 27% 31% 6%	4120
November	1st to 10th	Night	26% 3 9% 29% 25% 7%	2358
	11th to 20th	Night	29% 5% 8% 25% 29% 4	2470
	21st to end	Night	33% 4 9% 24% 24% 5%	2470
December	1st to 10th	Night	32% 5% 14% 28% 20% 2	2470
	11th to 20th	Night	35% 4 9% 29% 20% 3	3037
	21st to end	Night	46% 6% 10% 23% 12% 3	4532

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	20% 11% 34% 27% 8% 1	270
	11th to 20th	Day	23% 16% 39% 19% 3	270
	21st to end	Day	15% 9% 46% 24% 4 1	297
February	1st to 10th	Day	21% 17% 35% 24% 2 1	270
	11th to 20th	Day	16% 16% 41% 22% 4	270
	21st to end	Day	17% 20% 40% 17% 5%	225
March	1st to 10th	Day	19% 18% 36% 23% 5%	270
	11th to 20th	Day	23% 15% 34% 20% 7%	270
	21st to end	Day	24% 16% 39% 16% 5%	297
April	1st to 10th	Day	15% 21% 38% 21% 4	289
	11th to 20th	Day	18% 17% 35% 24% 6%	471
	21st to end	Day	23% 14% 35% 19% 8% 1	650
May	1st to 10th	Day	17% 12% 37% 25% 9% 1	653
	11th to 20th	Day	18% 11% 28% 27% 13% 3	675
	21st to end	Day	15% 11% 29% 25% 16% 4	734
June	1st to 10th	Day	5% 5% 21% 36% 25% 9%	680
	11th to 20th	Day	8% 4 26% 40% 18% 4	680
	21st to end	Day	5% 5% 26% 42% 19% 3	680
July	1st to 10th	Day	8% 3 16% 30% 31% 12%	671
	11th to 20th	Day	4 3 13% 38% 34% 8%	668
	21st to end	Day	8% 1 10% 33% 36% 11%	739
August	1st to 10th	Day	8% 3 15% 36% 31% 8%	676
	11th to 20th	Day	8% 2 16% 36% 31% 8%	665
	21st to end	Day	7% 2 11% 33% 37% 10%	648
September	1st to 10th	Day	12% 1 13% 31% 34% 9%	363
	11th to 20th	Day	6% 2 17% 38% 26% 10%	300
	21st to end	Day	15% 4 22% 34% 18% 6%	300
October	1st to 10th	Day	12% 5% 27% 26% 20% 10%	300
	11th to 20th	Day	8% 8% 46% 27% 10% 1	300
	21st to end	Day	24% 10% 34% 22% 8% 2	330
November	1st to 10th	Day	16% 10% 30% 27% 13% 2	291
	11th to 20th	Day	15% 13% 39% 21% 11% 2	270
	21st to end	Day	19% 13% 34% 25% 8%	270
December	1st to 10th	Day	11% 13% 39% 22% 13% 3	270
	11th to 20th	Day	17% 15% 31% 26% 9% 1	270
	21st to end	Day	16% 20% 39% 22% 2	297
January	1st to 10th	Night	12% 12% 38% 30% 8%	950
	11th to 20th	Night	15% 13% 39% 27% 6%	950
	21st to end	Night	13% 13% 39% 30% 6%	1045
February	1st to 10th	Night	15% 14% 39% 28% 4	950
	11th to 20th	Night	16% 14% 38% 29% 3	836
	21st to end	Night	15% 14% 39% 26% 5%	617
March	1st to 10th	Night	12% 12% 40% 31% 4	570
	11th to 20th	Night	18% 12% 34% 30% 5%	570
	21st to end	Night	19% 14% 38% 24% 4	627
April	1st to 10th	Night	13% 14% 40% 26% 6%	570
	11th to 20th	Night	16% 13% 39% 26% 6%	563
	21st to end	Night	17% 12% 37% 27% 6% 1	570
May	1st to 10th	Night	17% 8% 38% 31% 6% 1	570
	11th to 20th	Night	15% 6% 30% 33% 15%	561
	21st to end	Night	11% 6% 29% 33% 19% 2	617
June	1st to 10th	Night	5% 3 22% 42% 26% 1	570
	11th to 20th	Night	5% 3 27% 48% 17%	570
	21st to end	Night	6% 2 33% 42% 15% 1	570
July	1st to 10th	Night	7% 3 14% 43% 31% 2	555
	11th to 20th	Night	3 1 16% 46% 33% 2	552
	21st to end	Night	7% 1 12% 44% 33% 3	624
August	1st to 10th	Night	6% 1 15% 48% 29% 2	567
	11th to 20th	Night	6% 2 13% 48% 29% 2	564
	21st to end	Night	4 1 14% 41% 37% 2	627
September	1st to 10th	Night	11% 1 18% 42% 26% 2	570
	11th to 20th	Night	10% 2 21% 38% 24% 4	570
	21st to end	Night	9% 4 22% 41% 20% 4	570
October	1st to 10th	Night	11% 3 27% 35% 21% 2	676
	11th to 20th	Night	14% 7% 40% 32% 7% 1	760
	21st to end	Night	17% 12% 32% 29% 10% 1	836
November	1st to 10th	Night	11% 9% 36% 32% 11% 1	818
	11th to 20th	Night	12% 13% 34% 32% 8% 1	950
	21st to end	Night	17% 11% 31% 32% 8%	950
December	1st to 10th	Night	14% 10% 36% 32% 8% 1	950
	11th to 20th	Night	18% 10% 36% 31% 5%	950
	21st to end	Night	17% 14% 34% 30% 5%	1045

Page generated at 2024-11-05 07:15:49. Version ac07

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