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 2024-01-12.

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% 3 5% 4 3 4 4 5% 7% 48%	74934
	Night	11% 5% 2 4 4 3 4 4 5% 7% 52%	74817
Transparency	Day	35% 6% 12% 25% 18% 3	74658
	Night	32% 5% 12% 26% 20% 5%	74613
Seeing	Day	13% 8% 27% 29% 18% 5%	14402
	Night	13% 9% 31% 33% 13% 1	24392

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	9% 7% 3 5% 5% 3 3 4 4 6% 51%	1707
	11th to 20th	Day	13% 8% 3 6% 4 2 3 3 5% 6% 46%	1634
	21st to end	Day	11% 7% 3 7% 5% 3 4 3 4 6% 46%	1782
February	1st to 10th	Day	15% 9% 3 6% 5% 3 3 3 3 6% 44%	1620
	11th to 20th	Day	11% 7% 3 7% 5% 3 4 4 5% 6% 45%	1676
	21st to end	Day	11% 8% 3 6% 4 3 5% 4 6% 7% 44%	1488
March	1st to 10th	Day	13% 7% 3 6% 5% 3 4 4 3 5% 47%	1980
	11th to 20th	Day	19% 9% 2 4 3 3 4 3 4 5% 44%	1980
	21st to end	Day	18% 9% 4 6% 5% 3 5% 4 4 6% 37%	2178
April	1st to 10th	Day	11% 7% 2 4 5% 2 4 4 4 8% 48%	1998
	11th to 20th	Day	15% 7% 2 6% 5% 3 4 4 5% 6% 43%	2151
	21st to end	Day	18% 8% 3 5% 5% 3 3 4 4 6% 41%	2340
May	1st to 10th	Day	18% 6% 3 6% 6% 4 4 4 4 6% 39%	2340
	11th to 20th	Day	14% 7% 3 5% 5% 3 4 5% 5% 7% 43%	2302
	21st to end	Day	14% 7% 3 6% 7% 4 6% 5% 7% 9% 33%	2531
June	1st to 10th	Day	6% 4 2 4 5% 3 5% 5% 6% 10% 51%	2340
	11th to 20th	Day	9% 3 2 4 4 4 5% 4 5% 9% 51%	2340
	21st to end	Day	6% 3 2 3 4 2 5% 4 6% 8% 58%	2340
July	1st to 10th	Day	8% 4 2 5% 4 4 5% 6% 7% 9% 47%	2340
	11th to 20th	Day	4 3 2 3 4 2 5% 5% 6% 9% 56%	2340
	21st to end	Day	8% 5% 2 4 5% 3 6% 6% 6% 8% 46%	2546
August	1st to 10th	Day	8% 4 2 4 5% 2 5% 6% 7% 9% 48%	2328
	11th to 20th	Day	8% 3 2 4 5% 3 4 5% 5% 9% 52%	2301
	21st to end	Day	7% 3 1 4 3 3 4 5% 5% 8% 57%	2480
September	1st to 10th	Day	13% 4 2 4 4 2 4 4 4 6% 53%	2040
	11th to 20th	Day	11% 4 2 5% 3 3 4 5% 4 7% 51%	1980
	21st to end	Day	9% 4 2 4 4 2 3 4 4 6% 58%	1980
October	1st to 10th	Day	9% 6% 2 5% 5% 3 4 4 5% 6% 52%	1860
	11th to 20th	Day	11% 4 1 3 3 1 3 4 5% 7% 59%	1800
	21st to end	Day	15% 6% 2 4 3 2 3 3 4 5% 53%	1980
November	1st to 10th	Day	9% 6% 1 3 3 2 3 3 4 6% 60%	1806
	11th to 20th	Day	9% 5% 2 4 4 3 3 3 3 6% 59%	1710
	21st to end	Day	14% 6% 2 4 3 1 3 3 3 6% 56%	1710
December	1st to 10th	Day	10% 7% 2 5% 4 3 4 5% 4 7% 50%	1710
	11th to 20th	Day	12% 8% 3 5% 5% 3 5% 3 4 5% 46%	2161
	21st to end	Day	14% 11% 7% 9% 5% 3 4 4 5% 6% 31%	3135
January	1st to 10th	Night	8% 7% 3 5% 4 3 4 3 5% 6% 53%	2458
	11th to 20th	Night	11% 7% 3 5% 4 3 3 4 5% 6% 50%	2366
	21st to end	Night	9% 7% 4 5% 4 2 3 3 4 5% 55%	2574
February	1st to 10th	Night	11% 9% 4 6% 5% 3 4 4 4 6% 46%	2340
	11th to 20th	Night	12% 7% 3 5% 4 3 3 4 4 6% 49%	2185
	21st to end	Night	13% 6% 2 4 4 2 3 4 4 7% 51%	1766
March	1st to 10th	Night	12% 5% 2 4 5% 3 4 4 5% 6% 50%	1980
	11th to 20th	Night	16% 6% 2 3 4 3 4 4 4 7% 48%	1980
	21st to end	Night	17% 8% 3 5% 5% 3 4 4 4 6% 40%	2178
April	1st to 10th	Night	10% 4 2 5% 4 2 3 4 5% 6% 53%	1962
	11th to 20th	Night	12% 6% 2 6% 4 2 3 3 4 7% 49%	1754
	21st to end	Night	15% 5% 2 4 5% 2 4 3 5% 5% 48%	1620
May	1st to 10th	Night	17% 5% 2 5% 4 2 4 3 5% 9% 44%	1620
	11th to 20th	Night	14% 5% 2 4 4 2 4 4 4 8% 49%	1593
	21st to end	Night	10% 5% 2 5% 5% 3 4 4 6% 11% 45%	1745
June	1st to 10th	Night	4 3 2 4 3 3 5% 5% 6% 9% 55%	1620
	11th to 20th	Night	4 4 2 4 3 2 5% 5% 6% 12% 53%	1620
	21st to end	Night	6% 2 2 3 4 3 3 5% 6% 8% 59%	1620
July	1st to 10th	Night	7% 3 2 5% 4 2 4 4 6% 10% 52%	1620
	11th to 20th	Night	3 3 1 3 3 2 4 4 6% 10% 60%	1620
	21st to end	Night	6% 4 2 5% 4 3 4 6% 7% 10% 48%	1772
August	1st to 10th	Night	5% 3 1 3 5% 4 5% 6% 7% 10% 51%	1611
	11th to 20th	Night	6% 3 2 4 4 3 5% 5% 7% 7% 54%	1600
	21st to end	Night	4 2 2 3 3 3 4 4 4 9% 62%	1876
September	1st to 10th	Night	11% 3 1 4 4 2 3 4 4 5% 59%	1916
	11th to 20th	Night	10% 4 2 4 4 2 4 6% 6% 7% 52%	1980
	21st to end	Night	7% 2 2 4 3 3 4 4 5% 6% 62%	1980
October	1st to 10th	Night	10% 4 2 5% 4 2 3 4 4 5% 57%	2080
	11th to 20th	Night	12% 5% 1 3 3 2 3 3 4 6% 60%	2160
	21st to end	Night	14% 5% 2 3 4 2 3 3 4 4 56%	2376
November	1st to 10th	Night	9% 4 2 3 4 1 3 3 3 4 63%	2267
	11th to 20th	Night	9% 5% 2 3 3 2 4 4 4 7% 57%	2470
	21st to end	Night	13% 7% 3 3 3 2 3 3 3 5% 55%	2470
December	1st to 10th	Night	10% 6% 2 4 3 3 3 4 5% 7% 52%	2470
	11th to 20th	Night	11% 6% 3 5% 4 3 3 3 4 6% 52%	3036
	21st to end	Night	17% 8% 5% 7% 5% 3 4 4 4 6% 38%	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	35% 4 12% 25% 21% 2	1708
	11th to 20th	Day	39% 5% 12% 28% 15% 1	1634
	21st to end	Day	39% 4 14% 26% 15% 2	1782
February	1st to 10th	Day	44% 4 11% 26% 11% 3	1620
	11th to 20th	Day	39% 5% 12% 25% 15% 3	1685
	21st to end	Day	40% 5% 10% 23% 17% 6%	1488
March	1st to 10th	Day	41% 4 8% 21% 19% 7%	1980
	11th to 20th	Day	44% 4 9% 23% 16% 3	1980
	21st to end	Day	49% 6% 11% 23% 9% 2	2178
April	1st to 10th	Day	34% 6% 14% 24% 18% 4	1998
	11th to 20th	Day	42% 4 11% 24% 15% 3	2151
	21st to end	Day	45% 5% 10% 26% 13% 1	2340
May	1st to 10th	Day	47% 6% 11% 19% 15% 2	2340
	11th to 20th	Day	40% 7% 14% 24% 14%	2306
	21st to end	Day	46% 9% 15% 20% 9% 1	2531
June	1st to 10th	Day	27% 10% 18% 27% 16% 2	2340
	11th to 20th	Day	31% 6% 12% 29% 19% 2	2340
	21st to end	Day	22% 7% 16% 29% 21% 5%	2340
July	1st to 10th	Day	31% 9% 15% 26% 16% 3	2276
	11th to 20th	Day	22% 9% 15% 30% 20% 4	2271
	21st to end	Day	30% 9% 18% 26% 17% 1	2405
August	1st to 10th	Day	29% 9% 17% 27% 15% 2	2314
	11th to 20th	Day	29% 7% 13% 30% 19% 2	2301
	21st to end	Day	26% 7% 14% 25% 20% 8%	2480
September	1st to 10th	Day	32% 6% 12% 25% 18% 7%	2040
	11th to 20th	Day	33% 5% 11% 25% 23% 3	1980
	21st to end	Day	28% 5% 10% 23% 29% 5%	1980
October	1st to 10th	Day	32% 6% 12% 23% 23% 3	1860
	11th to 20th	Day	26% 5% 10% 26% 27% 7%	1800
	21st to end	Day	35% 4 11% 23% 19% 7%	1980
November	1st to 10th	Day	26% 5% 10% 31% 23% 6%	1806
	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	33% 3 10% 29% 20% 4	2458
	11th to 20th	Night	35% 4 10% 30% 18% 3	2366
	21st to end	Night	32% 3 13% 30% 18% 4	2574
February	1st to 10th	Night	41% 4 12% 24% 15% 4	2340
	11th to 20th	Night	38% 4 12% 26% 17% 3	2186
	21st to end	Night	35% 5% 9% 24% 19% 8%	1766
March	1st to 10th	Night	35% 5% 9% 22% 20% 8%	1980
	11th to 20th	Night	37% 5% 12% 20% 20% 5%	1980
	21st to end	Night	46% 5% 11% 21% 14% 2	2178
April	1st to 10th	Night	30% 6% 12% 24% 23% 6%	1962
	11th to 20th	Night	36% 5% 13% 23% 19% 5%	1754
	21st to end	Night	37% 6% 13% 22% 18% 3	1620
May	1st to 10th	Night	39% 6% 15% 22% 15% 3	1620
	11th to 20th	Night	34% 6% 15% 26% 17% 1	1594
	21st to end	Night	33% 8% 20% 26% 11% 1	1746
June	1st to 10th	Night	24% 8% 18% 30% 17% 2	1620
	11th to 20th	Night	24% 8% 16% 30% 19% 4	1620
	21st to end	Night	22% 7% 13% 31% 22% 5%	1620
July	1st to 10th	Night	25% 8% 15% 30% 19% 3	1575
	11th to 20th	Night	19% 6% 13% 31% 25% 5%	1566
	21st to end	Night	29% 8% 14% 28% 19% 1	1673
August	1st to 10th	Night	24% 10% 16% 33% 14% 4	1601
	11th to 20th	Night	26% 8% 10% 28% 24% 3	1600
	21st to end	Night	20% 6% 14% 27% 24% 8%	1876
September	1st to 10th	Night	27% 5% 11% 28% 20% 9%	1916
	11th to 20th	Night	31% 6% 11% 22% 25% 5%	1980
	21st to end	Night	22% 5% 9% 27% 31% 7%	1980
October	1st to 10th	Night	29% 5% 10% 21% 27% 9%	2080
	11th to 20th	Night	27% 4 7% 27% 27% 8%	2160
	21st to end	Night	32% 4 8% 23% 27% 7%	2376
November	1st to 10th	Night	25% 3 9% 30% 25% 7%	2267
	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% 12% 33% 27% 8% 1	270
	11th to 20th	Day	24% 14% 41% 18% 2	245
	21st to end	Day	13% 11% 49% 23% 4	264
February	1st to 10th	Day	20% 18% 35% 23% 3 1	240
	11th to 20th	Day	18% 16% 40% 23% 4	240
	21st to end	Day	18% 22% 37% 18% 4 1	198
March	1st to 10th	Day	19% 19% 35% 22% 5%	240
	11th to 20th	Day	26% 13% 34% 18% 8%	240
	21st to end	Day	24% 16% 40% 15% 5%	264
April	1st to 10th	Day	14% 20% 39% 22% 5%	258
	11th to 20th	Day	19% 16% 35% 24% 6%	429
	21st to end	Day	22% 14% 35% 19% 8% 1	600
May	1st to 10th	Day	17% 12% 36% 25% 10% 1	603
	11th to 20th	Day	19% 11% 29% 25% 13% 3	625
	21st to end	Day	16% 10% 29% 23% 17% 5%	679
June	1st to 10th	Day	5% 4 21% 36% 25% 9%	630
	11th to 20th	Day	8% 3 26% 40% 19% 3	630
	21st to end	Day	5% 5% 24% 42% 20% 3	630
July	1st to 10th	Day	8% 3 14% 31% 32% 13%	621
	11th to 20th	Day	4 3 11% 38% 36% 9%	618
	21st to end	Day	8% 1 9% 34% 37% 11%	684
August	1st to 10th	Day	8% 2 14% 36% 32% 7%	626
	11th to 20th	Day	8% 2 15% 35% 33% 8%	615
	21st to end	Day	7% 2 11% 32% 38% 11%	599
September	1st to 10th	Day	13% 1 13% 29% 35% 9%	330
	11th to 20th	Day	7% 2 16% 37% 26% 11%	270
	21st to end	Day	14% 4 21% 36% 18% 6%	270
October	1st to 10th	Day	13% 6% 27% 26% 18% 10%	270
	11th to 20th	Day	9% 8% 49% 25% 9% 1	270
	21st to end	Day	26% 10% 32% 23% 8% 2	297
November	1st to 10th	Day	14% 10% 31% 27% 14% 3	270
	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% 12% 38% 28% 6%	910
	21st to end	Night	11% 13% 40% 30% 6%	990
February	1st to 10th	Night	15% 14% 39% 28% 4	900
	11th to 20th	Night	16% 14% 39% 29% 3	791
	21st to end	Night	16% 14% 38% 26% 5%	582
March	1st to 10th	Night	13% 12% 40% 31% 5%	540
	11th to 20th	Night	19% 12% 34% 29% 6%	540
	21st to end	Night	19% 14% 39% 23% 4 1	594
April	1st to 10th	Night	13% 14% 39% 27% 6%	540
	11th to 20th	Night	17% 13% 37% 27% 6%	533
	21st to end	Night	17% 12% 38% 27% 6% 1	540
May	1st to 10th	Night	17% 7% 37% 31% 6% 1	540
	11th to 20th	Night	15% 6% 30% 34% 15%	531
	21st to end	Night	10% 6% 29% 33% 20% 3	584
June	1st to 10th	Night	5% 3 22% 42% 27% 1	540
	11th to 20th	Night	5% 3 27% 48% 17%	540
	21st to end	Night	6% 2 32% 43% 16% 1	540
July	1st to 10th	Night	7% 2 13% 43% 32% 2	525
	11th to 20th	Night	2 1 14% 46% 34% 2	522
	21st to end	Night	7% 1 12% 44% 33% 3	591
August	1st to 10th	Night	6% 1 14% 47% 30% 2	537
	11th to 20th	Night	6% 2 12% 49% 30% 2	534
	21st to end	Night	5% 1 14% 39% 39% 2	594
September	1st to 10th	Night	11% 1 19% 41% 26% 2	540
	11th to 20th	Night	11% 2 21% 37% 24% 4	540
	21st to end	Night	9% 4 23% 41% 20% 4	540
October	1st to 10th	Night	12% 3 28% 33% 21% 3	640
	11th to 20th	Night	14% 7% 40% 31% 7% 1	720
	21st to end	Night	17% 11% 32% 29% 10% 1	792
November	1st to 10th	Night	11% 9% 37% 31% 11% 1	787
	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 2024-01-09 15:24:27. Version ac07

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